Assessment on Ultimate Load of Cold-formed Steel Channel (CFSC Stub Column
Directory of Open Access Journals (Sweden)
Mohd Sani Mohd Syahrul Hisyam
2015-01-01
Full Text Available Cold-formed steel is used as the non-structural and structural material in civil engineering work and building. Cold-formed steel channel is selected and cut into 100 mm, 200 mm, 300 mm, 400 mm and 500 mm. The slenderness ratio is calculated and noted as a stub or short column because below 40. The column is tested by using Universal Testing Machine to determine the ultimate load of the stub column. Besides, the CFSC is determined the material properties of CFSC for checking it’s the originality of steel based material. The experimental data are tested and compared with the Direct Strength Method (DSM. It showed that the CFSC1 with a height of 100 mm is reported to have a higher value of ultimate load when compared with other samples. When the height of the stub column increased, the ultimate load of the sample is decreased. Then, the CFSC1 also showed a higher in initial stiffness when compared with other samples. All samples are shown having a higher data in ultimate load when compared with the Direct Strength Method prediction. The ultimate load of experimental and DSM all gave a ratio below 1.03. Finally, all samples can further recommend determining the relation between the ultimate loads with variations of height of the column.
Directory of Open Access Journals (Sweden)
Song Bing
2016-01-01
Full Text Available Taking the mixing amount of diatomite calcined and vitrified micro bubbles(VMB as the main changing parameters, experiment studies the properties of the vitrified micro bubbles recycled concrete blocks; then this paper adopts the finite element software ANSYS to analyze the square double skin steel stub short columns filled with recycled concrete under axial compression. According to the vertical stress distribution, strain and bearing capacity of the steel tube and core concrete, we make a contrastive axial compression properties analysis on the different hollow ratio χ(0,0.35and the VMB content(0%,100%,130% of square double skin steel stub short columns filled with recycled concrete. The result shows that: Compressive strength of VMB recycled concrete increases with the increase of diatomite calcined content, when mixing amount of diatomite calcined is 3%,the compressive strength of 130% VMB content test specimen can reach 32.45 MPa;Because of the inner circular steel tube is setted which strengthening component buckling capacity and improving the ductility of the component, stress distribution of hollow components is more balance than solid components, and their axial displacements decrease by 5.6% compared with the solid components when they reach ultimate bearing capacity; When the hollow ratio is same, ultimate bearing capacity of 130% VMB content test specimen compared with the content is 0% only reduces by about 3.5%; When the VMB content is same, ultimate bearing capacity of hollow components compared with solid components increases by about 2.5%, which reducing weight as well as improving the anti-seismic performance.
International Nuclear Information System (INIS)
Hu, Jong Wan; Leon, Roberto T; Choi, Eunsoo
2011-01-01
In this research, three structural design concepts are integrated: the use of composite concrete-filled tube (CFT) columns, the use of partially restrained (PR) connections and the introduction of innovative materials (shape memory alloys) in the connection design. These concepts are used to enhance the robustness and performance of composite-special moment frames. These innovative connections intend to exploit the recentering properties of super-elastic SMA tension bars, the energy dissipation capacity of low-carbon steel bars and the toughness of CFT columns. PR-CFT connection prototypes were designed based on a hierarchy of strength models for each connection component. Simplified user joint elements based on the mechanical modeling approach were formulated in an effort to simulate the realistic behavior of bolted connections. The application of new connections to low-rise PR composite frames is illustrated by designing four buildings in both 2D and 3D for the western US region. The performance of these composite frames was compared with those with conventional welded frames in terms of strength, ductility and recentering behavior. In all three areas, frames with the PR composite connections showed superior performance. This is due primarily to the capability of this system to redistribute inter-story drift more evenly through the height of the frame
Directory of Open Access Journals (Sweden)
Mahmood Yahyai
2015-12-01
Full Text Available Column-tree moment resisting frames, as the efficient shop-welded and field-bolted structural systems, are used in many countries. Very limited research has been carried out on such systems under fire conditions. This paper presents experimental investigations of the behavior of beam and bolted splice connections in steel column-tree moment resisting frames exposed to fire. Two full-scale steel sub-frames with different splice connections were tested under ISO 834 standard fire. The flange splice plates were configured as a single plate with single shear bolts in first specimen, and as double plates with double shear bolts in second specimen. The observation of thermal and structural fire behaviors including temperature histories, temperature-deflection of the beam, temperature-rotation of splice connections and failure modes were investigated. The temperature-deflection and temperature-rotation curves remained in the elastic range until about 600°C. Beyond 600°C, the behavior would be highly nonlinear plastic. The beam splice connection failed due to shear fracture of top bolts at temperatures beyond 750°C. Consequently, stub beam web failed at those temperatures because of block-shear. Using double plates with double shear bolts for flange splices would enhance the temperature resistance and rotational capacity of the beam splice connections. Both tests results confirmed that specimens retain the capacity to support the design load when the average beam temperature does not exceed 600°C. This temperature limit confirms the temperature criteria provided by ASTM E119 and ANSI/UL 263 for a restrained beam, and can be used to specify the minimum fire resistance criteria for beams in column-tree MRFs. The measured time-deflection curves showed that the restrained fire resistance rating for both unprotected specimens obtained about 15 minutes in both tests.
Energy Technology Data Exchange (ETDEWEB)
Nakai, H.; Kitada, T. [Osaka City Univ. (Japan); Oryu, T. [Kawasaki Heavy Industries Ltd., Kobe (Japan)
1998-10-21
Thin-walled box stub columns such as beams of cable-stayed bridge, suspension bridge tower, arch rib of arch bridge and steel piers and so forth can also bear torsion at the same time besides compression and bending. These thin-walled box stub columns may achieve ultimate condition before reaching to plastic condition due to the effect of local buckling and so forth. Accordingly, it is the important topic to study the properties regarding ultimate strength of thin-walled box members in order to evaluate correctly the effect on load bearing resistance of local buckling. In this report, validity of load bearing resistance curve and ultimate strength interaction curve proposed by authors was studied using load bearing capacity experiment results. As a result, all ultimate strengths obtained by the experiment were higher than the ultimate strengths estimated by load bearing capacity curve and ultimate strength interaction curve. Further, it was revealed that the specimens subjected to torsion or subjected to bending and torsion and so forth exceeded the plastic strength due to the effect of strain hardening. 12 refs., 14 figs., 4 tabs.
DEFF Research Database (Denmark)
Carl, Michael; Martinez, Mercedes Garcia; Mesa-Lao, Bartolomé
2014-01-01
This paper describes the most recent dataset that has been added to the CRITT Translation Process Research Database (TPR-DB). Under the name CFT13, this new study contains user activity data (UAD) in the form of key-logging and eye-tracking collected during the second CasMaCat field trial in June...
Three-stub quarter wave superconducting resonator design
Directory of Open Access Journals (Sweden)
N. R. Lobanov
2006-11-01
Full Text Available This paper describes a concept for superconducting resonators for the acceleration of ions in the velocity range β=v/c=0.015–0.04. Such a resonator operates in λ/4 mode with three loading elements and so can be thought of as a triple quarter wave resonator (3-QWR providing 4 accelerating gaps. The use of a column to support the three stubs provides a benefit beyond those of the two-stub design (2-QWR. In the 3-QWR, the rf mirror currents in the walls surrounding the stubs need only travel through 45° instead of the 90° in the 2-QWR thus further reducing the current in the demountable joints. As in the 2-QWR, the shape of the column allows control of the frequency splitting between the accelerating and other modes. The copper structure is designed to be coated by a thin superconducting film of niobium or lead for operation at 4.3 K. The particular device reported here operates at 150 MHz with an optimum β of 0.04. Its outer cylinder is the same size and shape as for the 2-QWR structure reported previously, in order to minimize construction and cryostat costs. A simple transmission line model is presented and the results of microwave studio and other numerical analyses are discussed. The 3-QWR resonators are appropriate for the upgrade of the low-velocity sections of the ANU Heavy Ion Accelerator Facility and other heavy ion accelerator boosters.
Finite element analysis of an extended end-plate connection using the T-stub approach
Energy Technology Data Exchange (ETDEWEB)
Muresan, Ioana Cristina; Balc, Roxana [Technical University of Cluj-Napoca, Faculty of Civil Engineering. 15 C Daicoviciu Str., 400020, Cluj-Napoca (Romania)
2015-03-10
Beam-to-column end-plate bolted connections are usually used as moment-resistant connections in steel framed structures. For this joint type, the deformability is governed by the deformation capacity of the column flange and end-plate under tension and elongation of the bolts. All these elements around the beam tension flange form the tension region of the joint, which can be modeled by means of equivalent T-stubs. In this paper a beam-to-column end-plate bolted connection is substituted with a T-stub of appropriate effective length and it is analyzed using the commercially available finite element software ABAQUS. The performance of the model is validated by comparing the behavior of the T-stub from the numerical simulation with the behavior of the connection as a whole. The moment-rotation curve of the T-stub obtained from the numerical simulation is compared with the behavior of the whole extended end-plate connection, obtained by numerical simulation, experimental tests and analytical approach.
Phonon heat transport through periodically stubbed waveguides
International Nuclear Information System (INIS)
Li Wenxia; Chen Keqiu
2006-01-01
We investigate the acoustic phonon band structure, transmission spectrum and thermal conductance in a periodically stubbed waveguide structure by use of the transfer matrix method and the scattering matrix method. We find that the existence of stop-frequencies or dips in the transmission spectrum, which corresponds to the stop bands or gaps in the acoustic band structure. The dependence of the stop band width and the dip width on the stub height is also demonstrated. We also find that the universal quantum thermal conductance can be clearly observed and the thermal conductance increases monotonically with increasing temperature. Our results show that the acoustic phonon band structure, transmission spectrum and thermal conductance can be artificially controlled by adjusting the height of the stub
Kostov, Ivan
2010-01-01
We study the quasiclassical expansion associated with a complex curve. In a more specific context this is the 1/N expansion in U(N)-invariant matrix integrals. We compare two approaches, the CFT approach and the topological recursion, and show their equivalence. The CFT approach reformulates the problem in terms of a conformal field theory on a Riemann surface, while the topological recursion is based on a recurrence equation for the observables representing symplectic invariants on the complex curve. The two approaches lead to two different graph expansions, one of which can be obtained as a partial resummation of the other.
Design and Analytical Evaluation of a New Self-Centering Connection with Bolted T-Stub Devices
Directory of Open Access Journals (Sweden)
Mahbobeh Mirzaie Aliabadi
2013-01-01
Full Text Available A new posttensioned T-stub connection (PTTC for earthquake resistant steel moment resisting frames (MRFs is introduced. The proposed connection consists of high strength posttensioned (PT strands and bolted T-stubs. The post-tensioning strands run through the column and are anchored against the flange of the exterior column. The T-stubs, providing energy dissipation, are bolted to the flange of beam and column and no field welding is required. The strands compress the T-stub against the column flange to develop the resisting moment to service loads and to provide a restoring force that returns the structure to its initial position following an earthquake. An analytical model based on fiber elements is developed in OpenSees to model PTTCs. The analytical model can predict the expected behavior of the new proposed connection under cyclic loading. PTTC provides similar characteristic behavior of the posttensioned connections. Both theoretical behavior and design methods are proposed, and the design methods are verified based on parametric studies and comparison to analytical results. The parametric studies prove the desired self-centering behavior of PTTC and show that this connection can reduce or eliminate the plastic rotation by its self-centering behavior as well as providing required strength and stiffness under large earthquake rotations.
Directory of Open Access Journals (Sweden)
Junwon Seo
2017-09-01
Full Text Available Partially restrained (PR bolted T-stub connections have been widely used in replacement of established fully restrained (FR welded connections, which are susceptible to sudden brittle failure. These bolted T-stub connections can permit deformation, easily exceeding the allowable limit without any fracture because they are constructed with a design philosophy whereby the plastic deformation concentrates on bolt fasteners made of ductile steel materials. Thus, the PR bolted connections take advantage of excellent energy dissipation capacity in their moment and rotation behavior. However, a considerable amount of residual deformation may occur at the bolted connection subjected to excessive plastic deformation, thereby requiring additional costs to recover the original configuration. In this study, superelastic shape memory alloy (SMA bolts, which have a recentering capability upon unloading, are fabricated so as to solve these drawbacks, and utilized by replacing conventional steel bolts in the PR bolted T-stub connection. Instead of the full-scale T-stub connection, simplified T-stub components subjected to axial force are designed on the basis of a basic equilibrium theory that transfers the bending moment from the beam to the column and can be converted into equivalent couple forces acting on the beam flange. The feasible failure modes followed by corresponding response mechanisms are taken into consideration for component design with superelastic SMA bolts. The inelastic behaviors of such T-stub components under cyclic loading are simulated by advanced three-dimensional (3D finite element (FE analysis. Finally, this study suggests an optimal design for smart recentering T-stub components with respect to recentering and energy dissipation after observing the FE analysis results.
Online monitoring of biofouling using coaxial stub resonator technique
Hoog-Antonyuk, N.A.; Mayer, M.J.J.; Miedema, H.; Olthuis, Wouter; Tomaszweska, A.A.; Paulitsch-Fuchs, A.H.; van den Berg, Albert
Here we demonstrate the proof-of-principle that a coaxial stub resonator can be used to detect early stages of biofilm formation. After promising field tests using a stub resonator with a stainless steel inner conductor as sensitive element, the sensitivity of the system was improved by using a
Energy Technology Data Exchange (ETDEWEB)
Alday, Luis F.; Bissi, Agnese; Łukowski, Tomasz [Mathematical Institute, University of Oxford,Andrew Wiles Building, Radcliffe Observatory Quarter,Woodstock Road, Oxford, OX2 6GG (United Kingdom)
2015-11-16
Using conformal field theory (CFT) arguments we derive an infinite number of constraints on the large spin expansion of the anomalous dimensions and structure constants of higher spin operators. These arguments rely only on analyticity, unitarity, crossing-symmetry and the structure of the conformal partial wave expansion. We obtain results for both, perturbative CFT to all order in the perturbation parameter, as well as non-perturbatively. For the case of conformal gauge theories this provides a proof of the reciprocity principle to all orders in perturbation theory and provides a new “reciprocity' principle for structure constants. We argue that these results extend also to non-conformal theories.
International Nuclear Information System (INIS)
Alday, Luis F.; Bissi, Agnese; Łukowski, Tomasz
2015-01-01
Using conformal field theory (CFT) arguments we derive an infinite number of constraints on the large spin expansion of the anomalous dimensions and structure constants of higher spin operators. These arguments rely only on analyticity, unitarity, crossing-symmetry and the structure of the conformal partial wave expansion. We obtain results for both, perturbative CFT to all order in the perturbation parameter, as well as non-perturbatively. For the case of conformal gauge theories this provides a proof of the reciprocity principle to all orders in perturbation theory and provides a new “reciprocity' principle for structure constants. We argue that these results extend also to non-conformal theories.
Energy Technology Data Exchange (ETDEWEB)
Turiaci, Gustavo J. [Physics Department, Princeton University,Princeton NJ 08544 (United States); Verlinde, Herman [Physics Department, Princeton University,Princeton NJ 08544 (United States); Princeton Center for Theoretical Science, Princeton University,Princeton NJ 08544 (United States)
2016-12-21
We make three observations that help clarify the relation between CFT and quantum chaos. We show that any 1+1-D system in which conformal symmetry is non-linearly realized exhibits two main characteristics of chaos: maximal Lyapunov behavior and a spectrum of Ruelle resonances. We use this insight to identify a lattice model for quantum chaos, built from parafermionic spin variables with an equation of motion given by a Y-system. Finally we point to a relation between the spectrum of Ruelle resonances of a CFT and the analytic properties of OPE coefficients between light and heavy operators. In our model, this spectrum agrees with the quasi-normal modes of the BTZ black hole.
International Nuclear Information System (INIS)
Turiaci, Gustavo J.; Verlinde, Herman
2016-01-01
We make three observations that help clarify the relation between CFT and quantum chaos. We show that any 1+1-D system in which conformal symmetry is non-linearly realized exhibits two main characteristics of chaos: maximal Lyapunov behavior and a spectrum of Ruelle resonances. We use this insight to identify a lattice model for quantum chaos, built from parafermionic spin variables with an equation of motion given by a Y-system. Finally we point to a relation between the spectrum of Ruelle resonances of a CFT and the analytic properties of OPE coefficients between light and heavy operators. In our model, this spectrum agrees with the quasi-normal modes of the BTZ black hole.
International Nuclear Information System (INIS)
Brodsky, Stanley J.; de Teramond, Guy F.
2007-01-01
The AdS/CFT correspondence between string theory in AdS space and conformal .eld theories in physical spacetime leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. Although QCD is not conformally invariant, one can nevertheless use the mathematical representation of the conformal group in five-dimensional anti-de Sitter space to construct a first approximation to the theory. The AdS/CFT correspondence also provides insights into the inherently non-perturbative aspects of QCD, such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable ζ which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions, the fundamental entities which encode hadron properties and allow the computation of decay constants, form factors, and other exclusive scattering amplitudes. New relativistic lightfront equations in ordinary space-time are found which reproduce the results obtained using the 5-dimensional theory. The effective light-front equations possess remarkable algebraic structures and integrability properties. Since they are complete and orthonormal, the AdS/CFT model wavefunctions can also be used as a basis for the diagonalization of the full light-front QCD Hamiltonian, thus systematically improving the AdS/CFT approximation
ANU LINAC upgrade using multi-stub resonators
Indian Academy of Sciences (India)
LINAC development work at ANU is currently aimed at improving ... current through the rf joint at the base of the outer wall and so increasing joint losses. The ... The stub geometry was developed with a help of Superfish/Poisson software [8].
Nodal Stub-Release in All-Optical Networks
DEFF Research Database (Denmark)
Ruepp, Sarah Renée; Buron, Jakob Due; Andriolli, Nicola
2008-01-01
In wavelength-routed networks, the scarcity of wavelength-converters severely impacts successful connection recovery. This can be mitigated by releasing the connection’s stubs (i.e. the surviving upstream and downstream span and node resources) prior to the restoration process. Releasing span...
Penedones, Joao
2017-01-01
We introduce the AdS/CFT correspondence as a natural extension of QFT in a fixed AdS background. We start by reviewing some general concepts of CFT, including the embedding space formalism. We then consider QFT in a fixed AdS background and show that one can define boundary operators that enjoy very similar properties as in a CFT, except for the lack of a stress tensor. Including a dynamical metric in AdS generates a boundary stress tensor and completes the CFT axioms. We also discuss some applications of the bulk geometric intuition to strongly coupled QFT. Finally, we end with a review of the main properties of Mellin amplitudes for CFT correlation functions and their uses in the context of AdS/CFT.
Energy Technology Data Exchange (ETDEWEB)
Li, Suobin; Chen, Tianning [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Wang, Xiaopeng, E-mail: xpwang@mail.xjtu.edu.cn [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Li, Yinggang [Key Laboratory of High Performance Ship Technology of Ministry of Education, Wuhan University of Technology, Wuhan, 430070 (China); Chen, Weihua [School of Mechanical Engineering and State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)
2016-06-03
We studied the expansion of locally resonant complete band gaps in two-dimensional phononic crystals (PCs) using a double-sided stubbed composite PC plate with composite stubs. Results show that the introduction of the proposed structure gives rise to a significant expansion of the relative bandwidth by a factor of 1.5 and decreases the opening location of the first complete band gap by a factor of 3 compared to the classic double-sided stubbed PC plate with composite stubs. Furthermore, more band gaps appear in the lower-frequency range (0.006). These phenomena can be attributed to the strong coupling between the “analogous rigid mode” of the stub and the anti-symmetric Lamb modes of the plate. The “analogous rigid mode” of the stub is produced by strengthening the localized resonance effect of the composite plates through the double-sided stubs, and is further strengthened through the introduction of composite stubs. The “analogous rigid mode” of the stubs expands the out-of-plane band gap, which overlaps with in-plane band gap in the lower-frequency range. As a result, the complete band gap is expanded and more complete band gaps appear. - Highlights: • Expansion of lower-frequency locally resonant BGs using novel composite phononic crystals plates. • The proposed structure expands the relative bandwidth 1.5 times compared to classic doubled-sided stubbed PC plates. • The opening location of the first complete BG decreases 3 times compared to the classic doubled-sided stubbed PC plates. • The concept “analogous rigid mode” is put forward to explain the expansion of lower-frequency BGs.
International Nuclear Information System (INIS)
Gu Benyuan.
1994-11-01
We present the numerical investigations on the conductance of the quantum waveguide containing an array of stubs with the use of the transfer matrix approach. The profiles of the conductance as functions of the stub length and of the Fermi wave number of electrons depend on the number of the stubs as also on the geometric configuration of the stubs. The conductance performance of this system for disordered stub lengths and disordered stub intervals is examined in detail. It is found that the localization length substantially depends on the type of disorder, the extent of disorder and the Fermi wave number of electrons. The influence of the stub interval disorder is less serious than that of the stub length disorder. For the same extent of disorder, the localization length associated with the stub length disorder is much shorter than that associated with the stub interval disorder. Root-mean-square value of the conductance fluctuations depends on the extent of disorder. We also present the statistical distribution of conductance fluctuations in this disorder network structure. It is found that the statistical distribution can be normal or log-normal, depending on the extent of disorder. Finally, we find that the additivity of the inverse of the localization lengths corresponding to the individual disorders and their combined disorder seems to be valid with good accuracy in the weak disorder regime. (author). 24 refs, 9 figs, 1 tab
Novel CFT duals for extreme black holes
International Nuclear Information System (INIS)
Chen Bin; Zhang Jiaju
2012-01-01
In this paper, we study the CFT duals for extreme black holes in the stretched horizon formalism. We consider the extremal RN, Kerr-Newman-AdS-dS, as well as the higher dimensional Kerr-AdS-dS black holes. In all these cases, we reproduce the well-established CFT duals. Actually we show that for stationary extreme black holes, the stretched horizon formalism always gives rise to the same dual CFT pictures as the ones suggested by ASG of corresponding near horizon geometries. Furthermore, we propose new CFT duals for 4D Kerr-Newman-AdS-dS and higher dimensional Kerr-AdS-dS black holes. We find that every dual CFT is defined with respect to a rotation in certain angular direction, along which the translation defines a U(1) Killing symmetry. In the presence of two sets of U(1) symmetry, the novel CFT duals are generated by the modular group SL(2,Z), and for n sets of U(1) symmetry there are general CFT duals generated by T-duality group SL(n,Z).
Analysis of double stub tuner control stability in a phased array antenna with strong cross-coupling
Energy Technology Data Exchange (ETDEWEB)
Wallace, G.M., E-mail: wallaceg@mit.edu [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States); Hillairet, J. [CEA-IRFM, Saint-Paul-lez-Durance (France); Koert, P.; Lin, Y.; Shiraiwa, S.; Wukitch, S.J. [MIT Plasma Science and Fusion Center, Cambridge, MA 02139 (United States)
2014-11-15
Highlights: • A novel method for reducing reflection coefficients for LHCD launchers is proposed and evaluated. • Numerical models of antenna behavior with stub tuning are analyzed. • The system is found to be stable under most realistic operating conditions. - Abstract: Active stub tuning with a fast ferrite tuner (FFT) has greatly increased the effectiveness of fusion ion cyclotron range of frequency (ICRF) systems (50–100 MHz) by allowing for the antenna system to respond dynamically to changes in the plasma load impedance such as during the L–H transition or edge localized modes (ELMs). A high power waveguide double-stub tuner is under development for use with the Alcator C-Mod lower hybrid current drive (LHCD) system at 4.6 GHz. The amplitude and relative phase shift between adjacent columns of an LHCD antenna are critical for control of the launched n{sub ||} spectrum. Adding a double-stub tuning network will perturb the phase and amplitude of the forward wave particularly if the unmatched reflection coefficient is high. This effect can be compensated by adjusting the phase of the low power microwave drive for each klystron amplifier. Cross-coupling of the reflected power between columns of the launcher must also be considered. The problem is simulated by cascading a scattering matrix for the plasma provided by a linear coupling model with the measured launcher scattering matrix and that of the FFTs. The solution is advanced in an iterative manner similar to the time-dependent behavior of the real system. System performance is presented under a range of edge density conditions from under-dense to over-dense and a range of launched n{sub ||}. Simulations predict power reflection coefficients (Γ{sup 2}) of less than 1% with no contamination of the n{sub ||} spectrum. Instability of the FFT tuning network can be problematic for certain plasma conditions and relative phasings, but reducing the control gain of the FFT network stabilizes the system.
Prototype for dS/CFT correspondence
International Nuclear Information System (INIS)
Gueijosa, Alberto; Lowe, David A.; Murugan, Jeff
2005-01-01
We consider dS 2 /CFT 1 where the asymptotic symmetry group of the de Sitter spacetime contains the Virasoro algebra. We construct representations of the Virasoro algebra realized in the Fock space of a massive scalar field in de Sitter space, built as excitations of the Euclidean vacuum state. These representations are unitary, without highest weight, and have vanishing central charge. They provide a prototype for a new class of conformal field theories dual to de Sitter backgrounds in string theory. The mapping of operators in the CFT to bulk quantities is described in detail. We comment on the extension to dS 3 /CFT 2
Online monitoring of biofouling using coaxial stub resonator technique
Directory of Open Access Journals (Sweden)
N.A. Hoog
2015-03-01
Analysis of the biofilm and the stub resonator signal, both as function of time, indicates that the sensor allows detection of early stages of biofilm formation. In addition, the sensor signal clearly discriminates between the first stages of biofilm formation (characterized by separated, individual spots of bacterial growth on the glass beads and the presence of a nearly homogeneous biofilm later on in time. Model simulations based on the transmission line theory predict a shift of the sensor response in the same direction and order of magnitude as observed in the biofouling experiments, thereby confirming the operating principle of the sensor.
Effective AdS/renormalized CFT
Fan, JiJi
2011-01-01
For an effective AdS theory, we present a simple prescription to compute the renormalization of its dual boundary field theory. In particular, we define anomalous dimension holographically as the dependence of the wave-function renormalization factor on the radial cutoff in the Poincare patch of AdS. With this definition, the anomalous dimensions of both single- and double- trace operators are calculated. Three different dualities are considered with the field theory being CFT, CFT with a dou...
CFT duals for extreme black holes
International Nuclear Information System (INIS)
Hartman, Thomas; Strominger, Andrew; Murata, Keiju; Nishioka, Tatsuma
2009-01-01
It is argued that the general four-dimensional extremal Kerr-Newman-AdS-dS black hole is holographically dual to a (chiral half of a) two-dimensional CFT, generalizing an argument given recently for the special case of extremal Kerr. Specifically, the asymptotic symmetries of the near-horizon region of the general extremal black hole are shown to be generated by a Virasoro algebra. Semiclassical formulae are derived for the central charge and temperature of the dual CFT as functions of the cosmological constant, Newton's constant and the black hole charges and spin. We then show, assuming the Cardy formula, that the microscopic entropy of the dual CFT precisely reproduces the macroscopic Bekenstein-Hawking area law. This CFT description becomes singular in the extreme Reissner-Nordstrom limit where the black hole has no spin. At this point a second dual CFT description is proposed in which the global part of the U(1) gauge symmetry is promoted to a Virasoro algebra. This second description is also found to reproduce the area law. Various further generalizations including higher dimensions are discussed.
Natsuume, Makoto
2015-01-01
This book describes applications of the AdS/CFT duality to the "real world." The AdS/CFT duality is an idea that originated from string theory and is a powerful tool for analyzing strongly-coupled gauge theories using classical gravitational theories. In recent years, it has been shown that one prediction of AdS/CFT is indeed close to the experimental result of the real quark–gluon plasma. Since then, the AdS/CFT duality has been applied to various fields of physics; examples are QCD, nuclear physics, condensed-matter physics, and nonequilibrium physics. The aim of this book is to provide background materials such as string theory, black holes, nuclear physics, condensed-matter physics, and nonequilibrium physics as well as key applications of the AdS/CFT duality in a single volume. The emphasis throughout the book is on a pedagogical and intuitive approach focusing on the underlying physical concepts. It also includes step-by-step computations for important results, which are useful for beginners. Th...
Evaluation of a quarterwave stub antenna for TIROS satellite application
Stogner, L. B.
1980-06-01
The TIROS-N quarterwave stub antenna communicated accurate position locations during low power level operations based on data processed by the Local User's Terminal (LUT) and Service ARGOS. This style of antenna is the marine mammal transmitter package. The antenna gain and radiation pattern and vertical polarization enhance the applicability. However, for marine mammal transmitter applications, a spring at the base of the antenna is required to provide flexibility and protection to the animal and the antenna must serve as a seawater sensor requiring it to be insulated from the seawater environment except at the sensory location. These problems appear solved for the NIMBUS system, and the TIROS system will be designed accordingly.
Introduction to AdS/CFT correspondence
Nastase, Horatiu
2015-01-01
Providing a pedagogical introduction to the rapidly developing field of AdS/CFT correspondence, this is one of the first texts to provide an accessible introduction to all the necessary concepts needed to engage with the methods, tools and applications of AdS/CFT. Without assuming anything beyond an introductory course in quantum field theory, it begins by guiding the reader through the basic concepts of field theory and gauge theory, general relativity, supersymmetry, supergravity, string theory and conformal field theory, before moving on to give a clear and rigorous account of AdS/CFT correspondence. The final section discusses the more specialised applications, including QCD, quark-gluon plasma and condensed matter. This book is self-contained and learner-focused, featuring numerous exercises and examples. It is essential reading for both students and researchers across the fields of particle, nuclear and condensed matter physics.
Energy Technology Data Exchange (ETDEWEB)
Freivogel, Ben; /Stanford U., Phys. Dept. /LBL, Berkeley; Hubeny, Veronika E.; /LBL, Berkeley /Durham U., Dept. of Math.; Maloney, Alexander; /Stanford U., Phys. Dept.; Myers, Rob; /Perimeter Inst. Theor. Phys. /Waterloo U.; Rangamani, Mukund; /LBL, Berkeley /Durham U., Dept. of Math.; Shenker, Stephen; /Stanford U., Phys. Dept.
2005-10-07
We study the realization of inflation within the AdS/CFT correspondence. We assume the existence of a string landscape containing at least one stable AdS vacuum and a (nearby) metastable de Sitter state. Standard arguments imply that the bulk physics in the vicinity of the AdS minimum is described by a boundary CFT. We argue that large enough bubbles of the dS phase, including those able to inflate, are described by mixed states in the CFT. Inflating degrees of freedom are traced over and do not appear explicitly in the boundary description. They nevertheless leave a distinct imprint on the mixed state. Analytic continuation allows us, in principle, to recover a large amount of nonperturbatively defined information about the inflating regime. Our work also shows that no scattering process can create an inflating region, even by quantum tunneling, since a pure state can never evolve into a mixed state under unitary evolution.We study the realization of inflation within the AdS/CFT correspondence. We assume the existence of a string landscape containing at least one stable AdS vacuum and a (nearby) metastable de Sitter state. Standard arguments imply that the bulk physics in the vicinity of the AdS minimum is described by a boundary CFT. We argue that large enough bubbles of the dS phase, including those able to inflate, are described by mixed states in the CFT. Inflating degrees of freedom are traced over and do not appear explicitly in the boundary description. They nevertheless leave a distinct imprint on the mixed state. Analytic continuation allows us, in principle, to recover a large amount of nonperturbatively defined information about the inflating regime. Our work also shows that no scattering process can create an inflating region, even by quantum tunneling, since a pure state can never evolve into a mixed state under unitary evolution.
Kerr-CFT and gravitational perturbations
International Nuclear Information System (INIS)
Dias, Oscar J.C.; Reall, Harvey S.; Santos, Jorge E.
2009-01-01
Motivated by the Kerr-CFT conjecture, we investigate perturbations of the near-horizon extreme Kerr spacetime. The Teukolsky equation for a massless field of arbitrary spin is solved. Solutions fall into two classes: normal modes and traveling waves. Imposing suitable (outgoing) boundary conditions, we find that there are no unstable modes. The explicit form of metric perturbations is obtained using the Hertz potential formalism, and compared with the Kerr-CFT boundary conditions. The energy and angular momentum associated with scalar field and gravitational normal modes are calculated. The energy is positive in all cases. The behaviour of second order perturbations is discussed.
Thermal geometry from CFT at finite temperature
Directory of Open Access Journals (Sweden)
Wen-Cong Gan
2016-09-01
Full Text Available We present how the thermal geometry emerges from CFT at finite temperature by using the truncated entanglement renormalization network, the cMERA. For the case of 2d CFT, the reduced geometry is the BTZ black hole or the thermal AdS as expectation. In order to determine which spacetimes prefer to form, we propose a cMERA description of the Hawking–Page phase transition. Our proposal is in agreement with the picture of the recent proposed surface/state correspondence.
Thermal geometry from CFT at finite temperature
Energy Technology Data Exchange (ETDEWEB)
Gan, Wen-Cong, E-mail: ganwencong@gmail.com [Department of Physics, Nanchang University, Nanchang 330031 (China); Center for Relativistic Astrophysics and High Energy Physics, Nanchang University, Nanchang 330031 (China); Shu, Fu-Wen, E-mail: shufuwen@ncu.edu.cn [Department of Physics, Nanchang University, Nanchang 330031 (China); Center for Relativistic Astrophysics and High Energy Physics, Nanchang University, Nanchang 330031 (China); Wu, Meng-He, E-mail: menghewu.physik@gmail.com [Department of Physics, Nanchang University, Nanchang 330031 (China); Center for Relativistic Astrophysics and High Energy Physics, Nanchang University, Nanchang 330031 (China)
2016-09-10
We present how the thermal geometry emerges from CFT at finite temperature by using the truncated entanglement renormalization network, the cMERA. For the case of 2d CFT, the reduced geometry is the BTZ black hole or the thermal AdS as expectation. In order to determine which spacetimes prefer to form, we propose a cMERA description of the Hawking–Page phase transition. Our proposal is in agreement with the picture of the recent proposed surface/state correspondence.
Avery, Steven G.; Chowdhury, Borun D.
2014-10-01
Several recent papers argue against firewalls by relaxing the requirement for locality outside the stretched horizon. In the firewall argument, locality essentially serves the purpose of ensuring that the degrees of freedom required for infall are those in the proximity of the black hole and not the ones in the early radiation. We make the firewall argument sharper by utilizing the AdS/CFT framework and claim that the firewall argument essentially states that the dual to a thermal state in the CFT is a firewall.
Chiral gravity, log gravity, and extremal CFT
International Nuclear Information System (INIS)
Maloney, Alexander; Song Wei; Strominger, Andrew
2010-01-01
We show that the linearization of all exact solutions of classical chiral gravity around the AdS 3 vacuum have positive energy. Nonchiral and negative-energy solutions of the linearized equations are infrared divergent at second order, and so are removed from the spectrum. In other words, chirality is confined and the equations of motion have linearization instabilities. We prove that the only stationary, axially symmetric solutions of chiral gravity are BTZ black holes, which have positive energy. It is further shown that classical log gravity--the theory with logarithmically relaxed boundary conditions--has finite asymptotic symmetry generators but is not chiral and hence may be dual at the quantum level to a logarithmic conformal field theories (CFT). Moreover we show that log gravity contains chiral gravity within it as a decoupled charge superselection sector. We formally evaluate the Euclidean sum over geometries of chiral gravity and show that it gives precisely the holomorphic extremal CFT partition function. The modular invariance and integrality of the expansion coefficients of this partition function are consistent with the existence of an exact quantum theory of chiral gravity. We argue that the problem of quantizing chiral gravity is the holographic dual of the problem of constructing an extremal CFT, while quantizing log gravity is dual to the problem of constructing a logarithmic extremal CFT.
AdS/CFT correspondence and supersymmetry
International Nuclear Information System (INIS)
Dobrev, V.K.
2002-05-01
We use the group-theoretic interpretation of the AdS/CFT correspondence which we proposed earlier in order to lift intertwining operators acting between boundary conformal representations to intertwining operators acting between bulk conformal representations. Further, we present the classification of the positive energy (lowest weight) unitary irreducible representations of the D=6 superconformal algebras osp(8*/2N). (author)
International Nuclear Information System (INIS)
Hubeny, Veronika E
2015-01-01
We give a brief review of the AdS/CFT correspondence, which posits the equivalence between a certain gravitational theory and a lower-dimensional non-gravitational one. This remarkable duality, formulated in 1997, has sparked a vigorous research program that has gained in breadth over the years, with applications to many aspects of theoretical (and even experimental) physics, not least to general relativity and quantum gravity. To put the AdS/CFT correspondence into historical context, we start by reviewing the relevant aspects of string theory (of which no prior knowledge is assumed). We then develop the statement of the correspondence, and explain how the two sides of the duality map into each other. Finally, we discuss the implications and applications of the correspondence, and indicate some of the current trends in this subject. The presentation attempts to convey the main concepts in a simple and self-contained manner, relegating supplementary remarks to footnotes. (paper)
Directory of Open Access Journals (Sweden)
Xiao-Peng Wang
2015-10-01
Full Text Available In this paper, the tuning characteristics of band gaps and waveguides in a locally resonant phononic crystal structure, consisting of multiple square stubs deposited on a thin homogeneous plate, are investigated. Using the finite element method and supercell technique, the dispersion relationships and power transmission spectra of those structures are calculated. In contrast to a system of one square stub, systems of multiple square stubs show wide band gaps at lower frequencies and an increased quantity of band gaps at higher frequencies. The vibration modes of the band gap edges are analyzed to clarify the mechanism of the generation of the lowest band gap. Additionally, the influence of the stubs arrangement on the band gaps in multi-stub systems is investigated. The arrangements of the stubs were found to influence the band gaps; this is critical to understand for practical applications. Based on this finding, a novel method to form defect scatterers by changing the arrangement of square stubs in a multi-stub perfect phononic crystal plate was developed. Defect bands can be induced by creating defects inside the original complete band gaps. The frequency can then be tuned by changing the defect scatterers’ stub arrangement. These results will help in fabricating devices such as acoustic filters and waveguides whose band frequency can be modulated.
International Nuclear Information System (INIS)
Kumazawa, R.; Saito, K.; Kasahara, H.; Seki, T.; Mutoh, T.; Shimpo, F.; Nomura, G.; Kato, A.; Okada, H.; Zhao, Y.; Kwak, J.G.; Yoon, J.S.
2008-01-01
Ion cyclotron range of frequency (ICRF) heating has been a reliable tool for steady-state plasma heating with high RF power of several tens of megawatts. However, a sudden increase in the reflected RF power during ICRF heating experiments with ELMy H-mode plasmas is an issue which must be solved for future fusion experimental devices or fusion reactors. This paper describes an innovative ICRF heating system using a frequency feedback control to reduce the reflected power in response to the rapid change in the plasma impedance in the ELMy H-mode plasma. A twin stub tuner has been newly invented for this purpose. The feasibility of keeping the reflected RF power fraction at a low level, e.g. 1%, is demonstrated even with a large change in plasma resistance, e.g. 2 ∼ 8Ω. Calculated and experimental results are presented for the conventional double stub tuner impedance matching system equipped with the twin stub tuner.
Multiband Bandstop Filter using an I-Stub-Loaded Meandered Defected Microstrip Structure
Directory of Open Access Journals (Sweden)
G. R. Koirala
2016-04-01
Full Text Available This paper presents a compact multiband bandstop filter (BSF that utilizes an I-stub embedded within a meandered defected microstrip structure (MDMS. The proposed design for obtaining a single stopband is analyzed by using a transmission line network model. On the basis of the single stopband structure, we designed and fabricated a dual- and tri-band bandstop filters operating at 2.5/6.78 GHz and 1.98/5.60/7.78 GHz, respectively, thereby exploring the concept of generating as many stopbands by simply adding the same number of I-stubs. The proposed filter also features the possibility of tuning the resonant frequencies by varying the width of the I-stubs.
Introduction to the AdS/CFT correspondence
de Boer, J.; Baulieu, L.; Benakli, K.; Douglas, M.R.; Mansoulié, B.; Rabinovici, E.; Cugliandolo, L.F.
2015-01-01
This chapter provides a summary of some of the most important aspects of the AdS/CFT correspondence, together with pointers to some of the vast number of papers that have been published on this subject. The AdS/CFT correspondence is one of the most exciting discoveries in theoretical physics of the
Amiri-Sharifi, S.; Ali-Akbari, M.; Kishani-Farahani, A.; Shafie, N.
2016-08-01
We exploit the AdS/CFT correspondence to investigate thermalization in an N = 2 strongly coupled gauge theory including massless fundamental matter (quark). More precisely, we consider the response of a zero temperature state of the gauge theory under influence of an external electric field which leads to a time-dependent current. The holographic dual of the above set-up is given by introducing a time-dependent electric field on the probe D7-brane embedded in an AdS5 ×S5 background. In the dual gravity theory an apparent horizon forms on the brane which, according to AdS/CFT dictionary, is the counterpart of the thermalization process in the gauge theory side. We classify different functions for time-dependent electric field and study their effect on the apparent horizon formation. In the case of pulse functions, where the electric field varies from zero to zero, apart from non-equilibrium phase, we observe the formation of two separate apparent horizons on the brane. This means that the state of the gauge theory experiences two different temperature regimes during its time evolution.
Xu, Yanlong
2015-08-01
The coupled mode theory with coupling of diffraction modes and waveguide modes is usually used on the calculations of transmission and reflection coefficients for electromagnetic waves traveling through periodic sub-wavelength structures. In this paper, I extend this method to derive analytical solutions of high-order dispersion relations for shear horizontal (SH) wave propagation in elastic plates with periodic stubs. In the long wavelength regime, the explicit expression is obtained by this theory and derived specially by employing an effective medium. This indicates that the periodical stubs are equivalent to an effective homogenous layer in the long wavelength. Notably, in the short wavelength regime, high-order diffraction modes in the plate and high-order waveguide modes in the stubs are considered with modes coupling to compute the band structures. Numerical results of the coupled mode theory fit pretty well with the results of the finite element method (FEM). In addition, the band structures\\' evolution with the height of the stubs and the thickness of the plate shows clearly that the method can predict well the Bragg band gaps, locally resonant band gaps and high-order symmetric and anti-symmetric thickness-twist modes for the periodically structured plates. © 2015 Elsevier B.V.
Xu, Yanlong
2015-01-01
structures' evolution with the height of the stubs and the thickness of the plate shows clearly that the method can predict well the Bragg band gaps, locally resonant band gaps and high-order symmetric and anti-symmetric thickness-twist modes
DEFF Research Database (Denmark)
Stadler, Robert; Markussen, Troels
2011-01-01
Asymmetric line shapes can occur in the transmission function describing electron transport in the vicinity of a minimum caused by quantum interference effects. Such asymmetry can be used to increase the thermoelectric efficiency of molecular junctions. So far, however, asymmetric line shapes hav...... calculations for a variety of t-stub molecules and also address their suitability for thermoelectric applications....
Fermions in nonrelativistic AdS/CFT correspondence
International Nuclear Information System (INIS)
Akhavan, Amin; Alishahiha, Mohsen; Davody, Ali; Vahedi, Ali
2009-01-01
We extend the nonrelativistic AdS/CFT correspondence to the fermionic fields. In particular, we study the two point function of a fermionic operator in nonrelativistic CFTs by making use of a massive fermion propagating in geometries with Schroedinger group isometry. Although the boundary of the geometries with Schroedinger group isometry differ from that in AdS geometries where the dictionary of AdS/CFT is established, using the general procedure of AdS/CFT correspondence, we see that the resultant two point function has the expected form for fermionic operators in nonrelativistic CFTs, though a nontrivial regularization may be needed.
Scaling dimensions in hidden Kerr/CFT correspondence
International Nuclear Information System (INIS)
Lowe, David A.; Messamah, Ilies; Skanata, Antun
2011-01-01
It has been proposed that a hidden conformal field theory (CFT) governs the dynamics of low frequency scattering in a general Kerr black hole background. We further investigate this correspondence by mapping higher order corrections to the massless wave equations in a Kerr background to an expansion within the CFT in terms of higher dimension operators. This implies the presence of infinite towers of CFT primary operators with positive conformal dimensions compatible with unitarity. The exact Kerr background softly breaks the conformal symmetry and the scaling dimensions of these operators run with frequency. The scale-invariant fixed point is dual to a degenerate case of flat spacetime.
Higher spin realization of the DS/CFT correspondence
International Nuclear Information System (INIS)
Anninos, Dionysios; Hartman, Thomas; Strominger, Andrew
2017-01-01
We conjecture that Vasiliev’s theory of higher spin gravity in four-dimensional de Sitter space (dS 4 ) is holographically dual to a three-dimensional conformal field theory (CFT 3 ) living on the spacelike boundary of dS 4 at future timelike infinity. The CFT 3 is the Euclidean Sp ( N ) vector model with anticommuting scalars. The free CFT 3 flows under a double-trace deformation to an interacting CFT 3 in the IR. We argue that both CFTs are dual to Vasiliev dS 4 gravity but with different future boundary conditions on the bulk scalar field. Our analysis rests heavily on analytic continuations of bulk and boundary correlators in the proposed duality relating the O ( N ) model with Vasiliev gravity in AdS 4 . (paper)
Two-stub quarter wave superconducting resonator design
Directory of Open Access Journals (Sweden)
N. R. Lobanov
2006-04-01
Full Text Available This paper describes the electromagnetic and mechanical properties of a 150 MHz λ/4, 3-gap structure with two loading elements, for the velocity range β=0.04–0.12 in the context of TEM-like λ/4 and λ/2 structures with multiple loading elements. A simple transmission lines model is presented and the results of Micro Wave Studio and simulations are discussed. The column of the multistub structures opens the opportunity to minimize current in locations allowing the exploitation of demountable joints and control the frequency splitting between the accelerating and other modes. These resonators are appropriate for the upgrade of the medium- and high-velocity sections of the ANU Heavy-Ion Accelerator Facility. Because of the broad velocity range for which such structures can be tailored, they can also be used in spallation neutron sources and rare isotope accelerators.
Compact Microstrip Triple-Mode Bandpass Filters Using Dual-Stub-Loaded Spiral Resonators
Directory of Open Access Journals (Sweden)
K. D. Xu
2017-04-01
Full Text Available Two new microstrip triple-mode resonators loaded with T-shaped open stubs using axially and centrally symmetric spiral structures, respectively, are presented. Spiraled for circuit size reduction, these two half-wavelength resonators can both generate three resonant modes over a wide frequency band by loading two T-stubs with different lengths. Due to the structural symmetry, they can be analyzed by odd- and even-mode method. To validate the design concept, two compact bandpass filters (BPFs using these two novel resonators with center frequencies of 1.76 GHz and 2.44 GHz for the GSM1800 and WLAN/Zigbee applications, respectively, have been designed, fabricated and tested. The center frequencies and bandwidths can be tunable through the analysis of resonant frequency responses, fractional bandwidths and external quality factor versus the resonator parameters. The final measured results have achieved good consistence with the simulations of these two BPFs.
Compact Dual-Band Bandpass Filter Using Stubs Loaded Ring Resonator
Xu, Jin
2016-01-01
This paper presents a novel second-order dual-band bandpass filter (BPF) by using proposed stubs loaded ring resonator. The resonant behavior of proposed stubs loaded ring resonator is analyzed by even-/odd-mode method, which shows its multiple-mode resonant characteristic. Parameters sweep is done so as to give the design guidelines. As an example, a second-order dual-band BPF operating at 1.8/5.2 GHz for GSM and WLAN applications is designed, fabricated and measured. The fabricated filter has a very compact size of 0.05λg×0.15λg. Measured results also show that the proposed dual-band BPF has a better than 20 dB rejection upper stopband from 5.47 GHz to 12.56 GHz. Good agreement is shown between the simulated and measured results.
On periodically driven AdS/CFT
Auzzi, Roberto; Gudnason, Sven Bjarke; Rabinovici, Eliezer
2013-01-01
We use the AdS/CFT correspondence to study a thermally isolated conformal field theory in four dimensions which undergoes a repeated deformation by an external periodic time-dependent source coupled to an operator of dimension Delta. The initial state of the theory is taken to be at a finite temperature. We compute the energy dissipated in the system as a function of the frequency and of the dimension Delta of the perturbing operator. This is done in the linear response regime. In order to study the details of thermalization in the dual field theory, the leading-order backreaction on the AdS black brane metric is computed. The evolution of the event and the apparent horizons is monitored; the increase of area in each cycle coincides with the increase in the equilibrium entropy corresponding to the amount of energy dissipated. The time evolution of the entanglement entropy of a spherical region and that of the two-points function of a probe operator with a large dimension are also inspected; we find a delay in...
Integrable theories that are asymptotically CFT
Evans, J M; Jonathan M Evans; Timothy J Hollowood
1995-01-01
A series of sigma models with torsion are analysed which generate their mass dynamically but whose ultra-violet fixed points are non-trivial conformal field theories -- in fact SU(2) WZW models at level k. In contrast to the more familiar situation of asymptotically free theories in which the fixed points are trivial, the sigma models considered here may be termed ``asymptotically CFT''. These theories have previously been conjectured to be quantum integrable; we confirm this by proposing a factorizable S-matrix to describe their infra-red behaviour and then carrying out a stringent test of this proposal. The test involves coupling the theory to a conserved charge and evaluating the response of the free-energy both in perturbation theory to one loop and directly from the S-matrix via the Thermodynamic Bethe Ansatz with a chemical potential at zero temperature. Comparison of these results provides convincing evidence in favour of the proposed S-matrix; it also yields the universal coefficients of the beta-func...
Behavior of concentrically loaded CFT braces connections
Directory of Open Access Journals (Sweden)
Maha M. Hassan
2014-03-01
Full Text Available Concrete filled tubes (CFTs composite columns have many economical and esthetic advantages, but the behavior of their connections is complicated. Through this study, it is aimed to investigate the performance and behavior of different connection configurations between concrete filled steel tube columns and bracing diagonals through an experimental program. The study included 12 connection subassemblies consisting of a fixed length steel tube and gusset plate connected to the tube end with different details tested under half cyclic loading. A notable effect was observed on the behavior of the connections due to its detailing changes with respect to capacity, failure mode, ductility, and stress distribution.
N=4 superconformal bootstrap of the K3 CFT
Energy Technology Data Exchange (ETDEWEB)
Lin, Ying-Hsuan; Shao, Shu-Heng [Jefferson Physical Laboratory, Harvard University,17 Oxford Street, Cambridge, MA 02138 (United States); Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study,1 Einstein Drive, Princeton, NJ 08540 (United States); Wang, Yifan [Center for Theoretical Physics, Massachusetts Institute of Technology,77 Massachusetts Ave, Cambridge, MA 02139 (United States); Yin, Xi [Jefferson Physical Laboratory, Harvard University,17 Oxford Street, Cambridge, MA 02138 (United States)
2017-05-23
We study two-dimensional (4,4) superconformal field theories of central charge c=6, corresponding to nonlinear sigma models on K3 surfaces, using the superconformal bootstrap. This is made possible through a surprising relation between the BPS N=4 superconformal blocks with c=6 and bosonic Virasoro conformal blocks with c=28, and an exact result on the moduli dependence of a certain integrated BPS 4-point function. Nontrivial bounds on the non-BPS spectrum in the K3 CFT are obtained as functions of the CFT moduli, that interpolate between the free orbifold points and singular CFT points. We observe directly from the CFT perspective the signature of a continuous spectrum above a gap at the singular moduli, and find numerically an upper bound on this gap that is saturated by the A{sub 1}N=4 cigar CFT. We also derive an analytic upper bound on the first nonzero eigenvalue of the scalar Laplacian on K3 in the large volume regime, that depends on the K3 moduli data. As two byproducts, we find an exact equivalence between a class of BPS N=2 superconformal blocks and Virasoro conformal blocks in two dimensions, and an upper bound on the four-point functions of operators of sufficiently low scaling dimension in three and four dimensional CFTs.
N=4 Superconformal Bootstrap of the K3 CFT
CERN. Geneva
2015-01-01
We study two-dimensional (4,4) superconformal field theories of central charge c=6, corresponding to nonlinear σ models on K3 surfaces, using the superconformal bootstrap. This is made possible through a surprising relation between the BPS N=4 superconformal blocks with c=6 and bosonic Virasoro conformal blocks with c=28, and an exact result on the moduli dependence of a certain integrated BPS 4-point function. Nontrivial bounds on the non-BPS spectrum in the K3 CFT are obtained as functions of the CFT moduli, that interpolate between the free orbifold points and singular CFT points. We observe directly from the CFT perspective the signature of a continuous spectrum above a gap at the singular moduli, and find numerically an upper bound on this gap that is saturated by the A1 N=4 cigar CFT. We also derive an analytic upper bound on the first nonzero eigenvalue of the scalar Laplacian on K3 in the large volume regime, that depends on the K3 moduli data. As two byproducts, we find an exact equivalence...
Algebraically special solutions in AdS/CFT
International Nuclear Information System (INIS)
Freitas, Gabriel Bernardi de; Reall, Harvey S.
2014-01-01
We investigate the AdS/CFT interpretation of the class of algebraically special solutions of Einstein gravity with a negative cosmological constant. Such solutions describe a CFT living in a 2+1 dimensional time-dependent geometry that, generically, has no isometries. The algebraically special condition implies that the expectation value of the CFT energy-momentum tensor is a local function of the boundary metric. When such a spacetime is slowly varying, the fluid/gravity approximation is valid and one can read off the values of certain higher order transport coefficients. To do this, we introduce a formalism for studying conformal, relativistic fluids in 2+1 dimensions that reduces everything to the manipulation of scalar quantities.
Algebraically special solutions in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Freitas, Gabriel Bernardi de; Reall, Harvey S. [Department of Applied Mathematics and Theoretical Physics, University of Cambridge,Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)
2014-06-26
We investigate the AdS/CFT interpretation of the class of algebraically special solutions of Einstein gravity with a negative cosmological constant. Such solutions describe a CFT living in a 2+1 dimensional time-dependent geometry that, generically, has no isometries. The algebraically special condition implies that the expectation value of the CFT energy-momentum tensor is a local function of the boundary metric. When such a spacetime is slowly varying, the fluid/gravity approximation is valid and one can read off the values of certain higher order transport coefficients. To do this, we introduce a formalism for studying conformal, relativistic fluids in 2+1 dimensions that reduces everything to the manipulation of scalar quantities.
Accelerated detectors and worldsheet horizons in AdS/CFT
Chernicoff, Mariano; Paredes, Angel
2010-01-01
We use the AdS/CFT correspondence to discuss the response of an accelerated observer to the quantum vacuum fluctuations. In particular, we study heavy quarks probing a strongly coupled CFT by analysing strings moving in AdS. We propose that, in this context, a non-trivial detection rate is associated to the existence of a worldsheet horizon and we find an Unruh-like expression for the worldsheet temperature. Finally, by examining a rotating string in global AdS we find that there is a transit...
Generalized Gribov-Lipatov Reciprocity and AdS/CFT
International Nuclear Information System (INIS)
Beccaria, M.; Macorini, G.; Forini, V.
2010-01-01
Planar □=4 SYM theory and QCD share the gluon sector, suggesting the investigation of Gribov-Lipatov reciprocity in the supersymmetric theory. Since the AdS/CFT correspondence links □=4 SYM and superstring dynamics on AdS 5 x S5, reciprocity is also expected to show up in the quantum corrected energies of certain classical string configurations dual to gauge theory twist-operators. We review recent results confirming this picture and revisiting the old idea of Gribov-Lipatov reciprocity as a modern theoretical tool useful for the study of open problems in AdS/CFT.
Seismic performance of a grout-repaired construction defect in a column plastic hinge
International Nuclear Information System (INIS)
Budek, A.
2006-01-01
A column built to test the use of high-strength transverse reinforcement in seismically-loaded shear-critical columns was found to have a construction defect. The column was built to be loaded in double bending and as such was expected to develop two plastic hinges, one at each end of column. In the plastic hinge region at the column top, a void was formed because the concrete could not pass through the load stub's reinforcing steel cage. This void was repaired using nonshrink grout placed in a fluid state. The column was tested after repair and performed satisfactorily. The grouted repair was able to support large plastic rotations and allowed the column to reach a high level of ductility. The only effects of the repair were slightly reduced concrete dilation and stiffness in the repaired hinge. (author)
Lee, Minseok; June, Seunghyeok; Kim, Sehwan
2018-01-01
Many biomedical applications require an efficient combination and localization of multiple discrete light sources ( e.g., fluorescence and absorbance imaging). We present a compact 6 channel combiner that couples the output of independent solid-state light sources into a single 400-μm-diameter fiber stub for handheld Internet of Things (IoT) devices. We demonstrate average coupling efficiencies > 80% for each of the 6 laser diodes installed into the prototype. The design supports the use of continuous wave and intensity-modulated laser diodes. This fiber-stub-type beam combiner could be used to construct custom multi-wavelength sources for tissue oximeters, microscopes and molecular imaging technologies. In order to validate its suitability, we applied the developed fiber-stub-type beam combiner to a multi-wavelength light source for a handheld IoT device and demonstrated its feasibility for smart healthcare through a tumor-mimicking silicon phantom.
Chen, Haidong; Che, Wenquan; Zhang, Tianyu; Cao, Yue; Feng, Wenjie
2018-06-01
Half-mode substrate integrated waveguide (HMSIW) switchable unit, built by HMSIW section with loaded single or multi-microstrip shunt stub(s), was proposed in this work. Both shorted and opened stubs were studied, investigated and compared, bandwidth enhancement method for proposed switchable units was proposed and demonstrated. Based on these switchable units, narrowband and broadband HMSIW single-pole-single-through (SPST) switches, SIW SPST switch and SIW/HMSIW-based single-pole-double-through (SPDT) switch were designed, fabricated and measured. Good performances were observed experimentally for these proposed circuits, showing the advantages of proposed concept and an excellent candidate for switchable or reconfigurable SIW/HMSIW circuits or systems.
Directory of Open Access Journals (Sweden)
Jiu-Jiu Chen
2017-11-01
Full Text Available The study for exotic topological effects of sound has attracted uprising interests in fundamental physics and practical applications. Based on the concept of valley pseudospin, we demonstrate the topological valley transport of plate-mode waves in a homogenous thin plate with periodic stubbed surface, where a deterministic two-fold Dirac degeneracy is form by two plate modes. We show that the topological property can be controlled by the height of stubs deposited on the plate. By adjusting the relative heights of adjacent stubs, the valley vortex chirality and band inversion are induced, giving rise to a phononic analog of valley Hall phase transition. We further numerically demonstrate the valley states of plate-mode waves with robust topological protection. Our results provide a new route to design unconventional elastic topological insulators and will significantly broaden its practical application in the engineering field.
Logarithmic corrections to entropy and AdS/CFT
Indian Academy of Sciences (India)
Abstract. We calculate the correction to the Bekenstein-Hawking entropy formula for five-dimensional AdS-Schwarzschild black holes due to thermodynamic fluctuations. The result is then compared with the boundary gauge theory entropy corrections via AdS/CFT correspondence.
Introduction to the AdS/CFT Correspondence
Nąstase, Horaǧiu
2015-09-01
Preface; Introduction; Part I. Background: 1. Elements of quantum field theory and gauge theory; 2. Basics of general relativity. Anti-de Sitter space; 3. Basics of supersymmetry; 4. Basics of supergravity; 5. Kaluza-Klein dimensional reduction; 6. Black holes and p-branes; 7. String theory actions and spectra; 8. Elements of conformal field theory; 9. D-branes; Part II. Basics of AdS/CFT for N = 4 SYM vs AdS5 × S5: 10. The AdS/CFT correspondence: motivation, definition and spectra; 11. Witten prescription and 3-point correlator calculations; 12. Holography in Lorentzian signature: Poincaré and global; 13. Solitonic objects in AdS/CFT; 14. Quarks and the Wilson loop; 15. Finite temperature and N = 4 SYM plasmas; 16. Scattering processes and gravitational shockwave limit; 17. The pp-wave correspondence; 18. Spin chains; Part III. AdS/CFT Developments and Gauge-Gravity Dualities: 19. Other conformal cases; 20. The 3 dimensional ABJM model vs. AdS4 × CP3; 21. Gravity duals; 22. Holographic renormalization; 23. RG flow between fixed points; 24. Phenomenological gauge-gravity duality I: AdS/QCD; 25. Phenomenological gauge-gravity duality II: AdS/CMT; 26. Gluon scattering: the Alday-Maldacena prescription; 27. Holographic entanglement entropy: the Ryu-Takayanagi prescription.
Extremal RN/CFT in both hands revisited
International Nuclear Information System (INIS)
Kuo, En-Jui; Yang, Yi
2016-01-01
We study RN/CFT correspondence for four dimensional extremal Reissner–Nordstrom black hole. We uplift the 4d RN black hole to a 5d rotating black hole and make a geometric regularization of the 5d space–time. Both hands central charges are obtained correctly at the same time by Brown–Henneaux technique.
An infalling observer in AdS/CFT
Papadodimas, Kyriakos; Raju, Suvrat
2013-01-01
We describe the experience of an observer falling into a black hole using the AdS/CFT correspondence. In order to do this, we reconstruct the local bulk operators measured by the observer along his trajectory outside the black hole. We then extend our construction beyond the black hole horizon. We
Topologically massive gravity and the AdS/CFT correspondence
International Nuclear Information System (INIS)
Skenderis, Kostas; Taylor, Marika; Rees, Balt C. van
2009-01-01
We set up the AdS/CFT correspondence for topologically massive gravity (TMG) in three dimensions. The first step in this procedure is to determine the appropriate fall off conditions at infinity. These cannot be fixed a priori as they depend on the bulk theory under consideration and are derived by solving asymptotically the non-linear field equations. We discuss in detail the asymptotic structure of the field equations for TMG, showing that it contains leading and subleading logarithms, determine the map between bulk fields and CFT operators, obtain the appropriate counterterms needed for holographic renormalization and compute holographically one- and two-point functions at and away from the 'chiral point' (μ = 1). The 2-point functions at the chiral point are those of a logarithmic CFT (LCFT) with c L = 0,c R = 3l/G N and b = -3l/G N , where b is a parameter characterizing different c = 0 LCFTs. The bulk correlators away from the chiral point (μ ≠ 1) smoothly limit to the LCFT ones as μ → 1. Away from the chiral point, the CFT contains a state of negative norm and the expectation value of the energy momentum tensor in that state is also negative, reflecting a corresponding bulk instability due to negative energy modes.
AdS/CFT correspondence in the Euclidean context
International Nuclear Information System (INIS)
Gottschalk, H.; Thaler, H.
2007-01-01
We study two possible prescriptions for AdS/CFT correspondence by means of functional integrals. The considerations are non-perturbative and reveal certain divergencies which turn out to be harmless, in the sense that reflection-positivity and conformal invariance are not destroyed. (orig.)
Degenerate stars and gravitational collapse in AdS/CFT
Arsiwala, X.; de Boer, J.; Papadodimas, K.; Verlinde, E.
2010-01-01
We construct composite CFT operators from a large number of fermionic primary fields corresponding to states that are holographically dual to a zero temperature Fermi gas in AdS space. We identify a large N regime in which the fermions behave as free particles. In the hydrodynamic limit the Fermi
Degenerate stars and gravitational collapse in AdS/CFT
Arsiwalla, X.; de Boer, J.; Papadodimas, K.; Verlinde, E.
2011-01-01
We construct composite CFT operators from a large number of fermionic primary fields corresponding to states that are holographically dual to a zero temperature Fermi gas in AdS space. We identify a large N regime in which the fermions behave as free particles. In the hydrodynamic limit the Fermi
Degenerate stars and gravitational collapse in AdS/CFT
Arsiwalla, Xerxes; de Boer, Jan; Papadodimas, Kyriakos; Verlinde, Erik
We construct composite CFT operators from a large number of fermionic primary fields corresponding to states that are holographically dual to a zero temperature Fermi gas in AdS space. We identify a large N regime in which the fermions behave as free particles. In the hydrodynamic limit the Fermi
Directory of Open Access Journals (Sweden)
Biljana P. Stošić
2011-12-01
Full Text Available This paper describes modeling and analyzing procedures for microstrip filters based on use of one-dimensional wave digital approach. Different filter structures are observed. One filter is based on quarter-wave length short-circuited stubs and connecting transmission lines. The other one is based on cross-junction opened stubs. Frequency responses are obtained by direct analysis of the block-based networks formed in Simulink toolbox of MATLAB environment. This wave-based method allows an accurate and efficient analysis of different microwave structures.
International Nuclear Information System (INIS)
Prat, J.P.
1985-01-01
Stub tubes have been installed on the control rod drive assemblies of the majority of boiling water reactor vessel bottoms. These stub tubes can undergo a slow process of cracking, producing no potential hazard but occasional plant unavailability due to leakage in excess of specification limits. In the case considered here, the development and application of remotely controlled equipment permitting access both from inside and outside the housing, and of crack evolution and location techniques, has made the progressive development, selection and planning of repairs a possibility, thus minimizing the risk of leakages appearing between refuelling outages. The example used here is of a Nuclear Power Plant in which a first leak appeared in 1981. Since that time extensive and progressive laboratory and field development work has been carried out. This paper presents the experience gained with customized, remote-control inspection equipment, and several developed or adapted techniques, as the basis for an in-service repair decision tree, the case in question being that of a BWR plant in which a cracking process, not affecting safety but potentially affecting availability, has given rise to leaks after ten years of operation
Energy Technology Data Exchange (ETDEWEB)
Satoh, K; Koizumi, D; Narahashi, S [Research Laboratories, NTT DoCoMo, Inc., 3-5 Hikari-no-oka, Yokosuka, Kanagwa, 239-8536 (Japan)], E-mail: satokei@nttdocomo.co.jp
2008-02-01
This paper presents a novel compact high temperature superconducting (HTS) bandpass filter (BPF) that employs a newly developed miniaturized coplanar-waveguide (CPW) quarter-wavelength resonators with strongly-coupled open stubs. The proposed resonator has a structure in which the open stubs are aligned close to the center conductor of the resonator. This is because strongly-coupled resonators have widely-split resonant frequencies, and the lowest resonant frequency is employed as the fundamental resonant frequency of the resonator in order to achieve miniaturization. The proposed resonator is 1.7 mm or less in length for use in the 5-GHz band, whereas the conventional straight resonator is approximately 6.4 mm long. A four-pole Chebyshev HTS BPF is designed and fabricated using the proposed CPW resonators. The entire length of the proposed four-pole filter is 15 mm. The frequency response of the fabricated filter agrees well with the electromagnetic simulation results. The proposed filter achieves a size reduction of at least 50% compared to previously reported filters without any degradation in the frequency characteristics.
Tunable Fano resonance in MDM stub waveguide coupled with a U-shaped cavity
Yi, Xingchun; Tian, Jinping; Yang, Rongcao
2018-04-01
A new compact metal-dielectric-metal waveguide system consisting of a stub coupled with a U-cavity is proposed to produce sharp and asymmetric Fano resonance. The transmission properties of the proposed structure are numerically studied by the finite element method and verified by the coupled mode theory. Simulation results reveal that the spectral profile can be easily tuned by adjusting the geometric parameters of the structure. One of the potential application of the proposed structure as a highly efficient plasmonic refractive index nanosensor was investigated with its sensitivity of more than 1000 nm/RIU and a figure of merit of up to 5500. Another application is integrated slow-light device whose group index can be greater than 6. In addition, multiple Fano resonances will occur in the broadband transmission spectrum by adding another U-cavity or (and) stub. The characteristics of the proposed structure are very promising for the highly performance filters, on-chip nanosensors, and slow-light devices.
Light-cone AdS/CFT-adapted approach to AdS fields/currents, shadows, and conformal fields
Energy Technology Data Exchange (ETDEWEB)
Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute, Leninsky prospect 53, Moscow 119991 (Russian Federation)
2015-10-16
Light-cone gauge formulation of fields in AdS space and conformal field theory in flat space adapted for the study of AdS/CFT correspondence is developed. Arbitrary spin mixed-symmetry fields in AdS space and arbitrary spin mixed-symmetry currents, shadows, and conformal fields in flat space are considered on an equal footing. For the massless and massive fields in AdS and the conformal fields in flat space, simple light-cone gauge actions leading to decoupled equations of motion are found. For the currents and shadows, simple expressions for all 2-point functions are also found. We demonstrate that representation of conformal algebra generators on space of currents, shadows, and conformal fields can be built in terms of spin operators entering the light-cone gauge formulation of AdS fields. This considerably simplifies the study of AdS/CFT correspondence. Light-cone gauge actions for totally symmetric arbitrary spin long conformal fields in flat space are presented. We apply our approach to the study of totally antisymmetric (one-column) and mixed-symmetry (two-column) fields in AdS space and currents, shadows, and conformal fields in flat space.
Energy Technology Data Exchange (ETDEWEB)
Li, Changsheng, E-mail: lcs135@163.com; Huang, Dan; Guo, Jierong
2015-02-20
We theoretically demonstrate that acoustic waves and optical waves can be spatially confined in the same micro-cavity by specially designed stubbed slab structure. The proposed structure presents both phononic and photonic band gaps from finite element calculation. The creation of cavity mode inside the band gap region provides strong localization of phonon and photon in the defect region. The practical parameters to inject cavity and work experimentally at telecommunication range are discussed. This structure can be precisely fabricated, hold promises to enhance acousto-optical interactions and design new applications as optomechanical resonator. - Highlights: • A resonator simultaneously supports acoustic and optical modes. • Strong spatial confinement and slow group velocity. • Potential to work as active optomechanical resonator.
Aspects of warped AdS3/CFT2 correspondence
Chen, Bin; Zhang, Jia-Ju; Zhang, Jian-Dong; Zhong, De-Liang
2013-04-01
In this paper we apply the thermodynamics method to investigate the holographic pictures for the BTZ black hole, the spacelike and the null warped black holes in three-dimensional topologically massive gravity (TMG) and new massive gravity (NMG). Even though there are higher derivative terms in these theories, the thermodynamics method is still effective. It gives consistent results with the ones obtained by using asymptotical symmetry group (ASG) analysis. In doing the ASG analysis we develop a brute-force realization of the Barnich-Brandt-Compere formalism with Mathematica code, which also allows us to calculate the masses and the angular momenta of the black holes. In particular, we propose the warped AdS3/CFT2 correspondence in the new massive gravity, which states that quantum gravity in the warped spacetime could holographically dual to a two-dimensional CFT with {c_R}={c_L}=24 /{Gm{β^2√{{2( {21-4{β^2}} )}}}}.
A CFT perspective on gravitational dressing and bulk locality
Energy Technology Data Exchange (ETDEWEB)
Lewkowycz, Aitor; Turiaci, Gustavo J. [Physics Department, Princeton University,Princeton, NJ 08544 (United States); Verlinde, Herman [Physics Department, Princeton University,Princeton, NJ 08544 (United States); Princeton Center for Theoretical Science, Princeton University,Princeton, NJ 08544 (United States)
2017-01-02
We revisit the construction of local bulk operators in AdS/CFT with special focus on gravitational dressing and its consequences for bulk locality. Specializing to 2+1-dimensions, we investigate these issues via the proposed identification between bulk operators and cross-cap boundary states. We obtain explicit expressions for correlation functions of bulk fields with boundary stress tensor insertions, and find that they are free of non-local branch cuts but do have non-local poles. We recover the HKLL recipe for restoring bulk locality for interacting fields as the outcome of a natural CFT crossing condition. We show that, in a suitable gauge, the cross-cap states solve the bulk wave equation for general background geometries, and satisfy a conformal Ward identity analogous to a soft graviton theorem. Virasoro symmetry, the large N conformal bootstrap and the uniformization theorem all play a key role in our derivations.
Accelerated detectors and worldsheet horizons in AdS/CFT
Chernicoff, Mariano; Paredes, Angel
2011-03-01
We use the AdS/CFT correspondence to discuss the response of an accelerated observer to the quantum vacuum fluctuations. In particular, we study heavy quarks probing a strongly coupled CFT by analysing strings moving in AdS. We propose that, in this context, a non-trivial detection rate is associated to the existence of a worldsheet horizon and we find an Unruh-like expression for the worldsheet temperature. Finally, by examining a rotating string in global AdS we find that there is a transition between string embeddings with and without worldsheet horizon. The dual picture corresponds to having non-trivial or trivial interaction with the quantum vacuum respectively. This is in qualitative agreement with results of Davies et al.
Rotating strings in confining AdS/CFT backgrounds
International Nuclear Information System (INIS)
Armoni, Adi; Barbon, Jose L.F.; Petkou, Anastasios C.
2002-01-01
We study semiclassical rotating strings in AdS/CFT backgrounds that exhibit both confinement and finite-size effects. The energy versus spin dispersion relation for short strings is the expected Regge trajectory behaviour, with the same string tension as is measured by the Wilson loop. Long strings probe the interplay between confinement and finite-size effects. In particular, the dispersion relation for long strings shows a characteristic dependence on the string tension and the finite-size scale. (author)
New results for AdS/CFT and beyond
International Nuclear Information System (INIS)
Bertolini, M.; Bigazzi, F.; Cotrone, A.L.
2006-01-01
We report on some recent results within the string/gauge theory correspondence, both in the conformal and in the non conformal cases, for a recently found class of N=1 dual pairs. These results provide the first cross check of AdS/CFT and field theory techniques like a-maximization. Moreover, they furnish new examples of cascading gauge theories and the first instance of 4d dynamical supersymmetry breaking embedded in the correspondence. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
Census taking in the hat: FRW/CFT duality
International Nuclear Information System (INIS)
Sekino, Yasuhiro; Susskind, Leonard
2009-01-01
In this paper a holographic description of eternal inflation is developed. We focus on the description of an open Friedmann-Robertson-Walker (FRW) universe that results from a tunneling event in which a false vacuum with positive vacuum energy decays to a supersymmetric vacuum with vanishing cosmological constant. The observations of a 'census taker' in the final vacuum can be organized into a holographic dual conformal field theory that lives on the asymptotic boundary of space. We refer to this bulk-boundary correspondence as FRW/CFT duality. The dual conformal field theory (CFT) is a Euclidean two-dimensional theory that includes a Liouville 2D gravity sector describing geometric fluctuations of the boundary. The renormalization-group flow of the theory is richer than in the AdS/CFT correspondence, and generates two space-time dimensions--one spacelike and one timelike. We discuss a number of phenomena such as bubble collisions, and the Garriga, Guth Vilenkin 'persistence of memory', from the dual viewpoint.
Condensed matter applications of AdS/CFT (I)
CERN. Geneva
2009-01-01
These lectures will discuss the application of ads/cft techniques to condensed matter systems. After motivating this endeavor, I will review the basic features of the ads/cft correspondence that will be used. I will review the physics of spectral functions and how they can be computed via AdS/CFT. Holographic superconductors will be discussed. The lectures will conclude with a discussion of open questions and future directions. References: - Holographic Superconductors. Sean A. Hartnoll, Christopher P. Herzog, Gary T. Horowitz, JHEP 0812:015,2008, arXiv:0810.1563 [hep-th] - Ohm's Law at strong coupling: S duality and the cyclotron resonance, Sean A. Hartnoll, Christopher P. Herzog, Phys.Rev.D76:106012,2007, arXiv:0706.3228 [hep-th] - Gravity duals for non-relativistic CFTs. Koushik Balasubramanian, John McGreevy, Phys.Rev.Lett.101:061601,2008, arXiv:0804.4053 [hep-th] - Toward an AdS/cold atoms correspondence: A Geometric realization of the Schrodinger symmetry. D.T. Son, Phys.Rev.D78:0...
Null infinity and extremal horizons in AdS-CFT
International Nuclear Information System (INIS)
Hickling, Andrew; Wiseman, Toby; Lucietti, James
2015-01-01
We consider AdS gravity duals to CFT on background spacetimes with a null infinity. Null infinity on the conformal boundary may extend to an extremal horizon in the bulk. For example it does so for Poincaré–AdS, although does not for planar Schwarzschild–AdS. If null infinity does extend into an extremal horizon in the bulk, we show that the bulk near-horizon geometry is determined by the geometry of the boundary null infinity. Hence the ‘infra-red’ geometry of the bulk is fixed by the large scale behaviour of the CFT spacetime. In addition the boundary stress tensor must have a particular decay at null infinity. As an application, we argue that for CFT on asymptotically flat backgrounds, any static bulk dual containing an extremal horizon extending from the boundary null infinity, must have the near-horizon geometry of Poincaré–AdS. We also discuss a class of boundary null infinity that cannot extend to a bulk extremal horizon, although we give evidence that they can extend to an analogous null surface in the bulk which possesses an associated scale-invariant ‘near-geometry’. (paper)
Towards causal patch physics in dS/CFT
Neiman, Yasha
2018-01-01
This contribution is a status report on a research program aimed at obtaining quantum-gravitational physics inside a cosmological horizon through dS/CFT, i.e. through a holographic description at past/future infinity of de Sitter space. The program aims to bring together two main elements. The first is the observation by Anninos, Hartman and Strominger that Vasiliev's higher-spin gravity provides a working model for dS/CFT in 3+1 dimensions. The second is the proposal by Parikh, Savonije and Verlinde that dS/CFT may prove more tractable if one works in so-called "elliptic" de Sitter space - a folded-in-half version of global de Sitter where antipodal points have been identified. We review some relevant progress concerning quantum field theory on elliptic de Sitter space, higher-spin gravity and its holographic duality with a free vector model. We present our reasons for optimism that the approach outlined here will lead to a full holographic description of quantum (higher-spin) gravity in the causal patch of a de Sitter observer.
Grimmett, E.S.
1964-01-01
This patent covers a continuous countercurrent liquidsolids contactor column having a number of contactor states each comprising a perforated plate, a layer of balls, and a downcomer tube; a liquid-pulsing piston; and a solids discharger formed of a conical section at the bottom of the column, and a tubular extension on the lowest downcomer terminating in the conical section. Between the conical section and the downcomer extension is formed a small annular opening, through which solids fall coming through the perforated plate of the lowest contactor stage. This annular opening is small enough that the pressure drop thereacross is greater than the pressure drop upward through the lowest contactor stage. (AEC)
Energy Technology Data Exchange (ETDEWEB)
Yoder, Karmen K.; Hutchins, Gary D.; Mock, Bruce H.; Fei, Xiangshu; Winkle, Wendy L. [Department of Radiology, Indiana University School of Medicine, L3-208, Indianapolis, IN 46202 (United States); Gitter, Bruce D.; Territo, Paul R. [Lilly Center for Anatomical and Molecular Imaging, Integrative Biology Division, Lilly Research Laboratories, Greenfield, IN 46140 (United States); Zheng Qihuang [Department of Radiology, Indiana University School of Medicine, L3-208, Indianapolis, IN 46202 (United States)], E-mail: qzheng@iupui.edu
2009-01-15
Introduction: Positron emission tomography scanning with radiolabeled phenyltropane cocaine analogs is important for quantifying the in vivo density of monoamine transporters, including the dopamine transporter (DAT). [{sup 11}C]{beta}-CFT is useful for studying DAT as a marker of dopaminergic innervation in animal models of psychiatric and neurological disorders. [{sup 11}C]{beta}-CFT is commonly labeled at the N-methyl position. However, labeling of [{sup 11}C]{beta}-CFT at the O-methyl position is a simpler procedure and results in a shorter synthesis time [desirable in small-animal studies, where specific activity (SA) is crucial]. In this study, we sought to validate that the O-methylated form of [{sup 11}C]{beta}-CFT provides equivalent quantitative results to that of the more commonly reported N-methyl form. Methods: Four female Sprague-Dawley rats were scanned twice on the IndyPET II small-animal scanner, once with [N-methyl-{sup 11}C]{beta}-CFT and once with [O-methyl-{sup 11}C]{beta}-CFT. DAT binding potentials (BP{identical_to}B'{sub avail}/K{sub d}) were estimated for right and left striata with a nonlinear least-squares algorithm, using a reference region (cerebellum) as the input function. Results: [N-Methyl-{sup 11}C]{beta}-CFT and [O-methyl-{sup 11}C]{beta}-CFT were synthesized with 40-50% radiochemical yields (HPLC purification). Radiochemical purity was >99%. SA at end of bombardment was 258{+-}30 GBq/{mu}mol. Average BP values for right and left striata with [N-methyl-{sup 11}C]{beta}-CFT were 1.16{+-}0.08 and 1.23{+-}0.14, respectively. BP values for [O-methyl-{sup 11}C]{beta}-CFT were 1.18{+-}0.08 (right) and 1.22{+-}0.16 (left). Paired t tests demonstrated that labeling position did not affect striatal DAT BP. Conclusions: These results suggest that [O-methyl-{sup 11}C]{beta}-CFT is quantitatively equivalent to [N-methyl-{sup 11}C]{beta}-CFT in the rat striatum.
Directory of Open Access Journals (Sweden)
Minghua Nie
2016-07-01
Full Text Available Posttranslational modifications (PTMs provide dynamic regulation of the cellular proteome, which is critical for both normal cell growth and for orchestrating rapid responses to environmental stresses, e.g. genotoxins. Key PTMs include ubiquitin, the Small Ubiquitin-like MOdifier SUMO, and phosphorylation. Recently, SUMO-targeted ubiquitin ligases (STUbLs were found to integrate signaling through the SUMO and ubiquitin pathways. In general, STUbLs are recruited to target proteins decorated with poly-SUMO chains to ubiquitinate them and drive either their extraction from protein complexes, and/or their degradation at the proteasome. In fission yeast, reducing or preventing the formation of SUMO chains can circumvent the essential and DNA damage response functions of STUbL. This result indicates that whilst some STUbL "targets" have been identified, the crucial function of STUbL is to antagonize SUMO chain formation. Herein, by screening for additional STUbL suppressors, we reveal crosstalk between the serine/threonine phosphatase PP2A-Pab1B55 and the SUMO pathway. A hypomorphic Pab1B55 mutant not only suppresses STUbL dysfunction, but also mitigates the phenotypes associated with deletion of the SUMO protease Ulp2, or mutation of the STUbL cofactor Rad60. Together, our results reveal a novel role for PP2A-Pab1B55 in modulating SUMO pathway output, acting in parallel to known critical regulators of SUMOylation homeostasis. Given the broad evolutionary functional conservation of the PP2A and SUMO pathways, our results could be relevant to the ongoing attempts to therapeutically target these factors.
International Nuclear Information System (INIS)
Brodsky, S
2008-01-01
The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable ζ which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection leads to AdS/CFT predictions for the analytic form of the frame-independent light-front wavefunctions (LFWFs) of mesons and baryons, the fundamental entities which encode hadron properties. The LFWFs in turn predict decay constants and spin correlations, as well as dynamical quantities such as form factors, structure functions, generalized parton distributions, and exclusive scattering amplitudes. Relativistic light-front equations in ordinary space-time are found which reproduce the results obtained using the fifth-dimensional theory and have remarkable algebraic structures and integrability properties. As specific examples we describe the behavior of the pion form factor in the space and time-like regions and determine the Dirac nucleon form factors in the space-like region. An extension to nonzero quark mass is used to determine hadronic distribution amplitudes of all mesons, heavy and light. We compare our results with the moments of the distribution amplitudes which have recently been computed from lattice gauge theory
Steel-reinforced concrete-filled steel tubular columns under axial and lateral cyclic loading
Farajpourbonab, Ebrahim; Kute, Sunil Y.; Inamdar, Vilas M.
2018-03-01
SRCFT columns are formed by inserting a steel section into a concrete-filled steel tube. These types of columns are named steel-reinforced concrete-filled steel tubular (SRCFT) columns. The current study aims at investigating the various types of reinforcing steel section to improve the strength and hysteresis behavior of SRCFT columns under axial and lateral cyclic loading. To attain this objective, a numerical study has been conducted on a series of composite columns. First, FEM procedure has been verified by the use of available experimental studies. Next, eight composite columns having different types of cross sections were analyzed. For comparison purpose, the base model was a CFT column used as a benchmark specimen. Nevertheless, the other specimens were SRCFT types. The results indicate that reinforcement of a CFT column through this method leads to enhancement in load-carrying capacity, enhancement in lateral drift ratio, ductility, preventing of local buckling in steel shell, and enhancement in energy absorption capacity. Under cyclic displacement history, it was observed that the use of cross-shaped reinforcing steel section causes a higher level of energy dissipation and the moment of inertia of the reinforcing steel sections was found to be the most significant parameter affecting the hysteresis behavior of SRCFT columns.
Logarithmic corrections to black hole entropy from Kerr/CFT
International Nuclear Information System (INIS)
Pathak, Abhishek; Porfyriadis, Achilleas P.; Strominger, Andrew; Varela, Oscar
2017-01-01
It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. Here we compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.
Logarithmic corrections to black hole entropy from Kerr/CFT
Energy Technology Data Exchange (ETDEWEB)
Pathak, Abhishek [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Porfyriadis, Achilleas P. [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Department of Physics, UCSB,Santa Barbara, CA 93106 (United States); Strominger, Andrew [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Varela, Oscar [Center for the Fundamental Laws of Nature, Harvard University,Cambridge, MA 02138 (United States); Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut),Am Mühlenberg 1, D-14476 Potsdam (Germany); Department of Physics, Utah State University,Logan, UT 84322 (United States)
2017-04-14
It has been shown by A. Sen that logarithmic corrections to the black hole area-entropy law are entirely determined macroscopically from the massless particle spectrum. They therefore serve as powerful consistency checks on any proposed enumeration of quantum black hole microstates. Sen’s results include a macroscopic computation of the logarithmic corrections for a five-dimensional near extremal Kerr-Newman black hole. Here we compute these corrections microscopically using a stringy embedding of the Kerr/CFT correspondence and find perfect agreement.
Gravitational collapse, chaos in CFT correlators and the information paradox
Energy Technology Data Exchange (ETDEWEB)
Farahi, Arya, E-mail: aryaf@umich.edu; Pando Zayas, Leopoldo A., E-mail: lpandoz@umich.edu
2014-06-27
We consider gravitational collapse of a massless scalar field in asymptotically anti-de Sitter spacetime. Following the AdS/CFT dictionary we further study correlations in the field theory side by way of the Klein–Gordon equation of a probe scalar field in the collapsing background. We present evidence that in a certain regime the probe scalar field behaves chaotically, thus supporting Hawking's argument in the black hole information paradox proposing that although the information can be retrieved in principle, deterministic chaos impairs, in practice, the process of unitary extraction of information from a black hole. We emphasize that quantum chaos will change this picture.
Schwinger-Keldysh propagators from AdS/CFT correspondence
International Nuclear Information System (INIS)
Herzog, C.P.; Son, D.T.
2003-01-01
We demonstrate how to compute real-time Green's functions for a class of finite temperature field theories from their AdS gravity duals. In particular, we reproduce the two-by-two Schwinger-Keldysh matrix propagator from a gravity calculation. Our methods should work also for computing higher point lorentzian signature correlators. We elucidate the boundary condition subtleties which hampered previous efforts to build a lorentzian-signature AdS/CFT correspondence. For two-point correlators, our construction is automatically equivalent to the previously formulated prescription for the retarded propagator. (author)
Yangians, S-matrices and AdS/CFT
International Nuclear Information System (INIS)
Torrielli, Alessandro
2011-01-01
This review is meant to be an account of the properties of the infinite-dimensional quantum group (specifically, Yangian) symmetry lying behind the integrability of the AdS/CFT spectral problem. In passing, the chance is taken to give a concise anthology of basic facts concerning Yangians and integrable systems, and to store a series of remarks, observations and proofs the author has collected in a 5 year span of research on the subject. We hope this exercise will be useful for future attempts to study Yangians in field and string theories, with or without supersymmetry. (topical review)
Yangians, S-matrices and AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Torrielli, Alessandro, E-mail: alessandro.torrielli@york.ac.uk [Department of Mathematics, University of York, Heslington, York, YO10 5DD (United Kingdom)
2011-07-01
This review is meant to be an account of the properties of the infinite-dimensional quantum group (specifically, Yangian) symmetry lying behind the integrability of the AdS/CFT spectral problem. In passing, the chance is taken to give a concise anthology of basic facts concerning Yangians and integrable systems, and to store a series of remarks, observations and proofs the author has collected in a 5 year span of research on the subject. We hope this exercise will be useful for future attempts to study Yangians in field and string theories, with or without supersymmetry. (topical review)
A Low-Profile WLAN Antenna with Inductor and Tuning Stub for Broadband Impedance Matching
Directory of Open Access Journals (Sweden)
Woo-Su Kim
2014-01-01
Full Text Available This paper presents a low-profile multiband antenna suitable for wireless local area networks (WLANs, using a chip inductor and tuning stub for broadband impedance matching. The proposed antenna is compact 12×10×1 mm3 and covers three bands: 2.4-GHz (2.400–2.484 GHz, 5.2-GHz (5.150–5.350 GHz, and 5.8-GHz (5.725–5.825 GHz. The measured 10-dB bandwidths are 12.0% (2.28–2.57 GHz in the lower band for 2.4-GHz WLANs and 39.1% (4.81–7.15 GHz in the upper band for 5 GHz-WLANs. The measured peak gain of the antenna is between 2.7 and 4.39 dBi and the radiation patterns are omnidirectional.
A Natural Language for AdS/CFT Correlators
Energy Technology Data Exchange (ETDEWEB)
Fitzpatrick, A.Liam; /Boston U.; Kaplan, Jared; /SLAC; Penedones, Joao; /Perimeter Inst. Theor. Phys.; Raju, Suvrat; /Harish-Chandra Res. Inst.; van Rees, Balt C.; /YITP, Stony Brook
2012-02-14
We provide dramatic evidence that 'Mellin space' is the natural home for correlation functions in CFTs with weakly coupled bulk duals. In Mellin space, CFT correlators have poles corresponding to an OPE decomposition into 'left' and 'right' sub-correlators, in direct analogy with the factorization channels of scattering amplitudes. In the regime where these correlators can be computed by tree level Witten diagrams in AdS, we derive an explicit formula for the residues of Mellin amplitudes at the corresponding factorization poles, and we use the conformal Casimir to show that these amplitudes obey algebraic finite difference equations. By analyzing the recursive structure of our factorization formula we obtain simple diagrammatic rules for the construction of Mellin amplitudes corresponding to tree-level Witten diagrams in any bulk scalar theory. We prove the diagrammatic rules using our finite difference equations. Finally, we show that our factorization formula and our diagrammatic rules morph into the flat space S-Matrix of the bulk theory, reproducing the usual Feynman rules, when we take the flat space limit of AdS/CFT. Throughout we emphasize a deep analogy with the properties of flat space scattering amplitudes in momentum space, which suggests that the Mellin amplitude may provide a holographic definition of the flat space S-Matrix.
The Kerr/CFT Correspondence and its Extensions
Directory of Open Access Journals (Sweden)
Geoffrey Compère
2012-10-01
Full Text Available We present a first-principles derivation of the main results of the Kerr/CFT correspondence and its extensions using only tools from gravity and quantum field theory, filling a few gaps in the literature when necessary. Firstly, we review properties of extremal black holes that imply, according to semi-classical quantization rules, that their near-horizon quantum states form a centrally-extended representation of the one-dimensional conformal group. This motivates the conjecture that the extremal Kerr and Reissner–Nordström black holes are dual to the chiral limit of a two-dimensional CFT. We also motivate the existence of an SL (2,ℤ family of two-dimensional CFTs, which describe in their chiral limit the extremal Kerr–Newman black hole. We present generalizations in anti-de Sitter spacetime and discuss other matter-coupling and higher-derivative corrections. Secondly, we show how a near-chiral limit of these CFTs reproduces the dynamics of near-superradiant probes around near-extremal black holes in the semi-classical limit. Thirdly, we review how the hidden conformal symmetries of asymptotically-flat black holes away from extremality, combined with their properties at extremality, allow for a microscopic accounting of the entropy of non-extremal asymptotically-flat rotating or charged black holes. We conclude with a list of open problems.
Modifications to holographic entanglement entropy in warped CFT
Energy Technology Data Exchange (ETDEWEB)
Song, Wei; Wen, Qiang; Xu, Jianfei [Yau Mathematical Sciences Center, Tsinghua University,Beijing 100084 (China)
2017-02-13
In https://www.doi.org/10.1103/PhysRevLett.117.011602 it was observed that asymptotic boundary conditions play an important role in the study of holographic entanglement beyond AdS/CFT. In particular, the Ryu-Takayanagi proposal must be modified for warped AdS{sub 3} (WAdS{sub 3}) with Dirichlet boundary conditions. In this paper, we consider AdS{sub 3} and WAdS{sub 3} with Dirichlet-Neumann boundary conditions. The conjectured holographic duals are warped conformal field theories (WCFTs), featuring a Virasoro-Kac-Moody algebra. We provide a holographic calculation of the entanglement entropy and Rényi entropy using AdS{sub 3}/WCFT and WAdS{sub 3}/WCFT dualities. Our bulk results are consistent with the WCFT results derived by Castro-Hofman-Iqbal using the Rindler method. Comparing with https://www.doi.org/10.1103/PhysRevLett.117.011602, we explicitly show that the holographic entanglement entropy is indeed affected by boundary conditions. Both results differ from the Ryu-Takayanagi proposal, indicating new relations between spacetime geometry and quantum entanglement for holographic dualities beyond AdS/CFT.
The Goldstone equivalence theorem and AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Anand, Nikhil; Cantrell, Sean [Department of Physics & Astronomy, Johns Hopkins University,Baltimore, MD 21218 (United States)
2015-08-03
The Goldstone equivalence theorem allows one to relate scattering amplitudes of massive gauge fields to those of scalar fields in the limit of large scattering energies. We generalize this theorem under the framework of the AdS/CFT correspondence. First, we obtain an expression of the equivalence theorem in terms of correlation functions of creation and annihilation operators by using an AdS wave function approach to the AdS/CFT dictionary. It is shown that the divergence of the non-conserved conformal current dual to the bulk gauge field is approximately primary when computing correlators for theories in which the masses of all the exchanged particles are sufficiently large. The results are then generalized to higher spin fields. We then go on to generalize the theorem using conformal blocks in two and four-dimensional CFTs. We show that when the scaling dimensions of the exchanged operators are large compared to both their spins and the dimension of the current, the conformal blocks satisfy an equivalence theorem.
CFT/gravity correspondence on the isolated horizon
Energy Technology Data Exchange (ETDEWEB)
Ghosh, Amit, E-mail: amit.ghosh@saha.ac.in [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, 700064 Kolkata (India); Pranzetti, Daniele, E-mail: daniele.pranzetti@gravity.fau.de [Institute for Quantum Gravity, University of Erlangen-Nürnberg (FAU), Staudtstrasse 7/B2, 91058 Erlangen (Germany)
2014-12-15
A quantum isolated horizon can be modelled by an SU(2) Chern–Simons theory on a punctured 2-sphere. We show how a local 2-dimensional conformal symmetry arises at each puncture inducing an infinite set of new observables localised at the horizon which satisfy a Kac–Moody algebra. By means of the isolated horizon boundary conditions, we represent the gravitational flux degrees of freedom in terms of the zero modes of the Kac–Moody algebra defined on the boundary of a punctured disk. In this way, our construction encodes a precise notion of CFT/gravity correspondence. The higher modes in the algebra represent new nongeometric charges which can be represented in terms of free matter field degrees of freedom. When computing the CFT partition function of the system, these new states induce an extra degeneracy factor, representing the density of horizon states at a given energy level, which reproduces the Bekenstein's holographic bound for an imaginary Immirzi parameter. This allows us to recover the Bekenstein–Hawking entropy formula without the large quantum gravity corrections associated with the number of punctures.
QGP thermodynamics and Meson spectroscopy with AdS/CFT
Erdmenger, J.; Kaminski, M.; Rust, F.
In this talk we present applications of the AdS/CFT correspondence to strongly coupled sys- tems at finite temperature and particle density. The model we investigate contains adjoint matter described by the gauge multiplet of N = 4, as well as fundamental matter given by the hyper- multiplet of N = 2 Super Yang-Mills theory. In some aspects these systems can be thought of as models for the quark-gluon plasma. In the first part we review some properties of meson spectra obtained from these holographic models. We discuss the implications of finite temperature and particle density in these string- theory motivated setups. In particular, we find a broadening of the vector meson peaks in the relevant spectral function at finite density. However, we do not observe a movement of the reso- nances to lower frequencies. Moreover, we analyze the effects of strong coupling on heavy meson diffusion in medium. To do so we make use of an effective model with dipole interaction, which is valid for heavy quarks at arbitrary coupling strength. We calculate the momentum broadening — normalized to the in-medium mass shift — and compare the large ’t Hooft coupling AdS/CFT result with a perturbative result for weak coupling. We find that the momentum broadening is reduced at large ’t Hooft coupling, leading to increased relaxation time.
Fermionic halos at finite temperature in AdS/CFT
Argüelles, Carlos R.; Grandi, Nicolás E.
2018-05-01
We explore the gravitational backreaction of a system consisting in a very large number of elementary fermions at finite temperature, in asymptotically AdS space. We work in the hydrodynamic approximation, and solve the Tolman-Oppenheimer-Volkoff equations with a perfect fluid whose equation of state takes into account both the relativistic effects of the fermionic constituents, as well as its finite temperature effects. We find a novel dense core-diluted halo structure for the density profiles in the AdS bulk, similarly as recently reported in flat space, for the case of astrophysical dark matter halos in galaxies. We further study the critical equilibrium configurations above which the core undergoes gravitational collapse towards a massive black hole, and calculate the corresponding critical central temperatures, for two qualitatively different central regimes of the fermions: the diluted-Fermi case, and the degenerate case. As a probe for the dual CFT, we construct the holographic two-point correlator of a scalar operator with large conformal dimension in the worldline limit, and briefly discuss on the boundary CFT effects at the critical points.
On the performance of circular concrete-filled high strength steel columns under axial loading
Directory of Open Access Journals (Sweden)
Mohamed Mahmoud El-Heweity
2012-06-01
Full Text Available This work presents a numerical study to investigate the performance of circular high-strength steel tubes filled with concrete (CFT under monotonic axial loading. A model is developed to implement the material constitutive relationships and non-linearity. Calibration against previous experimental data shows good agreement. A parametric study is then conducted using the model and compared with codes provisions. Strength and ductility of confined concrete are of primary concern. Variables considered are yield stress of steel tube and column diameter. The assessment of column performance is based on axial load carrying capacities and enhancements of both strength and ductility due to confinement. Two parameters namely strength enhancement factor (Kf and ductility index (μ are clearly defined and introduced for assessment. Results indicate that both concrete strength and ductility of CFT columns are enhanced but to different extents. The ductile behaviors are significantly evident. The increase in yield stress of steel tube has a minimal effect on concrete strength but pronounced effect on concrete ductility. However, reduction in ductility is associated with using high-tensile steel of Grade 70. The overall findings indicate that the use of high-strength tube in CFT columns is not promising. This finding may seriously be considered in seismic design.
Five loop Konishi from AdS/CFT
International Nuclear Information System (INIS)
Bajnok, Zoltan; Hegedus, Arpad; Janik, Romuald A.; Lukowski, Tomasz
2010-01-01
We derive the perturbative five loop anomalous dimension of the Konishi operator in N=4 SYM theory from the integrable string sigma model by evaluating finite size effects using Luescher formulas adapted to multimagnon states at weak coupling. In addition, we derive the five loop wrapping contribution for the L=2 single impurity state in the β deformed theory, which may be within reach of a direct perturbative computation. The Konishi expression exhibits two new features - a modification of Asymptotic Bethe Ansatz quantization and sensitiveness to an infinite set of coefficients of the BES/BHL dressing phase. The result satisfies nontrivial self-consistency conditions - simple transcendentality structure and cancellation of μ-term poles. It may be a testing ground for the proposed AdS/CFT TBA systems.
A universal feature of CFT Rényi entropy
Energy Technology Data Exchange (ETDEWEB)
Perlmutter, Eric [DAMTP, Centre for Mathematical Sciences, University of Cambridge,Cambridge, CB3 0WA (United Kingdom)
2014-03-26
We show that for a d-dimensional CFT in flat space, the Rényi entropy S{sub q} across a spherical entangling surface has the following property: in an expansion around q=1, the first correction to the entanglement entropy is proportional to C{sub T}, the coefficient of the stress tensor vacuum two-point function, with a fixed d-dependent coefficient. This is equivalent to a similar statement about the free energy of CFTs living on S{sup 1}×ℍ{sup d−1} with inverse temperature β=2πq. In addition to furnishing a direct argument applicable to all CFTs, we exhibit this result using a handful of gravity and field theory computations. Knowledge of C{sub T} thus doubles as knowledge of Rényi entropies in the neighborhood of q=1, which we use to establish new results in 3d vector models at large N.
Interacting fields in real-time AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Botta-Cantcheff, Marcelo; Martínez, Pedro J. [Instituto de Física de La Plata, CCT La Plata, CONICET & Departamento de Física,Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Silva, Guillermo A. [Instituto de Física de La Plata, CCT La Plata, CONICET & Departamento de Física,Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Abdus Salam International Centre for Theoretical Physics, Associate Scheme,Strada Costiera 11, 34151 Trieste (Italy)
2017-03-28
We compute time-ordered 2- and 3-pt correlation functions of CFT scalar operators between generic in/out states. The calculation is holographically carried out by considering a non backreacting AdS scalar field with a λϕ{sup 3} self-interaction term on a combination of Euclidean and Lorentzian AdS sections following the Skenderis-van Rees prescription. We show that, although working in an essentially different set up, the final result for the 3-pt correlators agree with those of Rastelli et al. for Euclidean AdS. By analyzing the inner product between the in/out excited states in the large N approximation, we argue that a cubic bulk interaction deforms the excited states from coherent into squeezed. Finally, a diagrammatic interpretation of the results suggests some general properties for the n-point correlation functions between excited states.
New Penrose limits and AdS/CFT
DEFF Research Database (Denmark)
Grignani, Gianluca; Harmark, Troels; Marini, Andrea
2010-01-01
We find a new Penrose limit of AdS 5 × S 5 giving the maximally supersymmetric pp-wave background with two explicit space-like isometries. This is an important missing piece in studying the AdS/CFT correspondence in certain subsectors. In particular whereas the Penrose limit giving one space......-like isometry is useful for the SU(2) sector of N = 4 SYM, this new Penrose limit is instead useful for studying the SU(2|3) and SU(1, 2|3) sectors. In addition to the new Penrose limit of AdS 5 × S 5 we also find a new Penrose limit of AdS4 × ℂP 3....
Condensed matter applications of AdS/CFT (II)
CERN. Geneva
2009-01-01
AdS/CFT. Holographic superconductors will be discussed. The lectures will conclude with a discussion of open questions and future directions. References: - Holographic Superconductors. Sean A. Hartnoll, Christopher P. Herzog, Gary T. Horowitz, JHEP 0812:015,2008, arXiv:0810.1563 [hep-th] - Ohm's Law at strong coupling: S duality and the cyclotron resonance, Sean A. Hartnoll, Christopher P. Herzog, Phys.Rev.D76:106012,2007, arXiv:0706.3228 [hep-th] - Gravity duals for non-relativistic CFTs. Koushik Balasubramanian, John McGreevy, Phys.Rev.Lett.101:061601,2008, arXiv:0804.4053 [hep-th] - Toward an AdS/cold atoms correspondence: A Geometric realization of the Schrodinger symmetry. D.T. Son, Phys.Rev.D78:0...
Condensed matter applications of AdS/CFT (IV)
CERN. Geneva
2009-01-01
AdS/CFT. Holographic superconductors will be discussed. The lectures will conclude with a discussion of open questions and future directions. References: - Holographic Superconductors. Sean A. Hartnoll, Christopher P. Herzog, Gary T. Horowitz, JHEP 0812:015,2008, arXiv:0810.1563 [hep-th] - Ohm's Law at strong coupling: S duality and the cyclotron resonance, Sean A. Hartnoll, Christopher P. Herzog, Phys.Rev.D76:106012,2007, arXiv:0706.3228 [hep-th] - Gravity duals for non-relativistic CFTs. Koushik Balasubramanian, John McGreevy, Phys.Rev.Lett.101:061601,2008, arXiv:0804.4053 [hep-th] - Toward an AdS/cold atoms correspondence: A Geometric realization of the Schrodinger symmetry. D.T. Son, Phys.Rev.D78:0...
Condensed matter applications of AdS/CFT (III)
CERN. Geneva
2009-01-01
AdS/CFT. Holographic superconductors will be discussed. The lectures will conclude with a discussion of open questions and future directions. References: - Holographic Superconductors. Sean A. Hartnoll, Christopher P. Herzog, Gary T. Horowitz, JHEP 0812:015,2008, arXiv:0810.1563 [hep-th] - Ohm's Law at strong coupling: S duality and the cyclotron resonance, Sean A. Hartnoll, Christopher P. Herzog, Phys.Rev.D76:106012,2007, arXiv:0706.3228 [hep-th] - Gravity duals for non-relativistic CFTs. Koushik Balasubramanian, John McGreevy, Phys.Rev.Lett.101:061601,2008, arXiv:0804.4053 [hep-th] - Toward an AdS/cold atoms correspondence: A Geometric realization of the Schrodinger symmetry. D.T. Son, Phys.Rev.D78:046003,2008, arXi...
Loop effects in AdS/CFT and beyond
International Nuclear Information System (INIS)
Gubser, Steven S.
2003-01-01
Double-trace operators which are relevant deformations of large N conformal field theories give rise to renormalization group flows that can be studied on both sides of the AdS/CFT duality. One-loop calculations in AdS can be compared successfully to results derived in field theory using the Hubbard-Stratonovich transformation. The calculations do not rely on supersymmetry, and they apply in any dimension, provided the original conformal field theory and its AdS dual are well-defined. A speculative idea is proposed for solving the cosmological constant problem based on non-gravitational strings that become light as the universe expands. This is a summary of my talk presented at the Nishinomiya-Yukawa Symposium in Nishinomiya, Japan. (author)
Classical/quantum integrability in AdS/CFT
International Nuclear Information System (INIS)
Kazakov, V.A.; Marshakov, A.; Minahan, J.A.; Zarembo, K.
2004-01-01
We discuss the AdS/CFT duality from the perspective of integrable systems and establish a direct relationship between the dimension of single trace local operators composed of two types of scalar fields in N=4 super Yang-Mills and the energy of their dual semiclassical string states in AdS(5) x S(5). The anomalous dimensions can be computed using a set of Bethe equations, which for 'long' operators reduces to a Riemann-Hilbert problem. We develop a unified approach to the long wavelength Bethe equations, the classical ferromagnet and the classical string solutions in the SU(2) sector and present a general solution, governed by complex curves endowed with meromorphic differentials with integer periods. Using this solution we compute the anomalous dimensions of these long operators up to two loops and demonstrate that they agree with string-theory predictions. (author)
The AdS/CFT Correspondence and Holographic QCD
International Nuclear Information System (INIS)
Erlich, J.
2012-01-01
Holographic QCD is an extra-dimensional approach to modeling QCD resonances and their interactions. Holographic models encode information about chiral symmetry breaking, Weinberg sum rules, vector meson dominance, and other phenomenological features of QCD. There are two complementary approaches to holographic model building: a top-down approach which begins with string-theory brane configurations, and a bottom-up approach which is more phenomenological. In this talk I will describe the AdS/CFT correspondence, which motivates Holographic QCD, and the techniques used to build holographic models of QCD and to calculate observables in those models. I will also discuss an intriguing light cone approach to Holographic QCD discovered by Brodsky and De Teramond. (author)
Extremely Short Optical Pulses and Ads/CFT Compliance
Directory of Open Access Journals (Sweden)
Konobeeva N.N.
2015-01-01
Full Text Available Dynamics of few cycle optical pulses in non-Fermi liquid was considered. Energy spectrum of non-Fermi liquid was taken from the AdS/CFT compliance. Conditions of quasiparticle excitation existence were defined. Non-Fermi liquid parameters impact on the shape of few cycle pulses were estimated. It was shown that extremely short optical pulse propagation in the non-Fermi liquid is a stable pattern. The value of chemical potential has a significant impact on extremely short pulse shape. An increase in initial pulse amplitude does not result in pulse-shape distortions under its propagation in considered medium that is why the non-Fermi liquid can be used in applications inherent in extremely short pulse processing.
New Perspectives for QCD from AdS/CFT
International Nuclear Information System (INIS)
Brodsky, S
2006-01-01
The AdS/CFT correspondence between conformal field theory and string states in an extended space-time has provided new insights into not only hadron spectra, but also their light-front wavefunctions. We show that there is an exact correspondence between the fifth-dimensional coordinate of anti-de Sitter space z and a specific impact variable ζ which measures the separation of the constituents within the hadron in ordinary space-time. This connection allows one to predict the form of the light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and scattering amplitudes. A new relativistic Schroedinger light-cone equation is found which reproduces the results obtained using the fifth-dimensional theory
American experience in the implementation of AML / CFT system
Directory of Open Access Journals (Sweden)
Larin Dmitry
2016-01-01
Full Text Available This article presents a research into very specific matters and issues of creating and further improvement of Anti-Money Laundering and Combating the Financing of Terrorism system (abbreviated as AML/CFT in the USA. In contains a precise analysis of key elements of this system, as well as a deep look into the nature and purposes of financial intelligence “FinCEN”. Strong emphasis is laid on The US Foreign Account Tax Compliance Act (FATCA for the reason that, according to this Act, any foreign financial institution is legitimately forced to sign a special agreement with The US Internal Revenue Service (IRS, giving the Service power to maintain control over any American asset within its equity. The latter is understood as a legal right to investigate not only the accounts and property of American taxpayers, but to investigate any account or capital of any foreign institution having American shares or stocks.
Bulk locality and entanglement swapping in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Kelly, William R. [Center for Quantum Mathematics and Physics (QMAP),Department of Physics, University of California,Davis, CA 95616 (United States)
2017-03-29
Localized bulk excitations in AdS/CFT are produced by operators which modify the pattern of entanglement in the boundary state. We show that simple models — consisting of entanglement swapping operators acting on a qubit system or a free field theory — capture qualitative features of gravitational backreaction and reproduce predictions of the Ryu-Takayanagi formula. These entanglement swapping operators naturally admit multiple representations associated with different degrees of freedom, thereby reproducing the code subspace structure emphasized by Almheiri, Dong, and Harlow. We also show that the boundary Reeh-Schlieder theorem implies that equivalence of certain operators on a code subspace necessarily breaks down when non-perturbative effects are taken into account (as is expected based on bulk arguments).
Functional perturbative RG and CFT data in the ϵ -expansion
DEFF Research Database (Denmark)
Codello, A.; Safari, M.; Vacca, G. P.
2018-01-01
We show how the use of standard perturbative RG in dimensional regularization allows for a renormalization group-based computation of both the spectrum and a family of coefficients of the operator product expansion (OPE) for a given universality class. The task is greatly simplified by a straight......We show how the use of standard perturbative RG in dimensional regularization allows for a renormalization group-based computation of both the spectrum and a family of coefficients of the operator product expansion (OPE) for a given universality class. The task is greatly simplified...... several results for the whole family of renormalizable multi-critical models ϕ2 n. Whenever comparison is possible our RG results explicitly match the ones recently derived in CFT frameworks....
DEFF Research Database (Denmark)
Buhl-Mortensen, Isak; de Leeuw, Marius; Ipsen, Asger C.
2017-01-01
-time dependence of the theory’s Minkowski space propagators is handled by reformulating these as propagators in an effective AdS4. Subsequently, we initiate the computation of quantum corrections. The one-loop correction to the one-point function of any local gauge-invariant scalar operator is shown to receive......We build the framework for performing loop computations in the defect version of N = 4 super Yang-Mills theory which is dual to the probe D5-D3 brane system with background gauge-field flux. In this dCFT, a codimension-one defect separates two regions of space-time with different ranks of the gauge...
Boundary multi-trace deformations and Opens in AdS/CFT correspondence
International Nuclear Information System (INIS)
Petkou, Anastasios C.
2002-01-01
We argue that multi-trace deformations of the boundary CFT in AdS/CFT correspondence can arise through the OPE of single-trace operators. We work out the example of a scalar field in AdS 5 with cubic self interaction. By an appropriate reparametrization of the boundary data we are able to deform the boundary CFT by a marginal operator that couples to the conformal anomaly. Our method can be used in the analysis of multi-trace deformations in N=4 SYM where the OPEs of various single-trace operators are known. (author)
The inside outs of AdS{sub 3}/CFT{sub 2}: exact AdS wormholes with entangled CFT duals
Energy Technology Data Exchange (ETDEWEB)
Mandal, Gautam; Sinha, Ritam; Sorokhaibam, Nilakash [Department of Theoretical Physics, Tata Institute of Fundamental Research,Mumbai 400005 (India)
2015-01-09
We present the complete family of solutions of 3D gravity (Λ<0) with two asymptotically AdS exterior regions. The solutions are constructed from data at the two boundaries, which correspond to two independent and arbitrary stress tensors T{sub R},T-bar{sub R}, and T{sub L},T-bar{sub L}. The two exteriors are smoothly joined on to an interior region through a regular horizon. We find CFT duals of these geometries which are entangled states of two CFT’s. We compute correlators between general operators at the two boundaries and find perfect agreement between CFT and bulk calculations. We calculate and match the CFT entanglement entropy (EE) with the holographic EE which involves geodesics passing through the wormhole. We also compute a holographic, non-equilibrium entropy for the CFT using properties of the regular horizon. The construction of the bulk solutions here uses an exact version of Brown-Henneaux type diffeomorphisms which are asymptotically nontrivial and transform the CFT states by two independent unitary operators on the two sides. Our solutions provide an infinite family of explicit examples of the ER=EPR relation of Maldacena and Susskind http://dx.doi.org/10.1002/prop.201300020.
Directory of Open Access Journals (Sweden)
Stanisław Wociór
2013-12-01
Full Text Available Over a three-year period (1997-1999 investigations were conducted on the effect of 6 date of cut to the stub on tree trunk diameter, height and branching of sour cherry maidens in the nursery.On the Prunus mahaleb seedling rootstock were found no significant influen ce of the date between January, 15 - March, 30 of cut to the stub on growth of sour cherry maidens cv. ´Łutówka' (tree trunk diameter and branching and efficiency of nursery. The date of cutting in 15 April decreased trunk diameter and percent of the first quality trees.
Energy Technology Data Exchange (ETDEWEB)
Sekiya, N., E-mail: nsekiya@yamanashi.ac.jp; Sugiyama, S.
2014-09-15
Highlights: • We have developed a HTS five-pole dual-band bandpass filter using stub-loaded hair-pin resonators. • The proposed dual-band BPF can independently control of the center frequency. • Flexibly adjustment of the bandwidth can be achieved by the H-shaped waveguide. • The proposed BPF is evaluated by simulation and measurement with good agreement. - Abstract: A HTS dual-band bandpass filter is developed to obtain sharp-cut off characteristics for mobile communication systems. The filter is composed of five stub-loaded hair-pin resonators with H-shaped waveguides between them. The main advantage of the proposed filter is to allow independent control of the center frequency of the first and second bands. The bandwidths can be flexibly adjusted using the H-shaped waveguide. An electromagnetic simulator was used to design and analyze the filter, which have a 3.5-GHz center frequency and a 70-MHz (2%) bandwidth for the first band and a 5.0-GHz center frequency and a 100-MHz (2%) bandwidth for the second band. The filter was fabricated using YBa{sub 2}Cu{sub 3}O{sub y} thin film on an Al{sub 2}O{sub 3} substrate. Ground plane was fabricated using Au thin film. The measured frequency responses of the filter tally well with the simulated ones.
Tri-Band CPW-Fed Stub-Loaded Slot Antenna Design for WLAN/WiMAX Applications
Li, Jianxing; Guo, Jianying; He, Bin; Zhang, Anxue; Liu, Qing Huo
2016-11-01
A novel uniplanar CPW-fed tri-band stub-loaded slot antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. Dual resonant modes were effectively excited in the upper band by using two identical pairs of slot stubs and parasitic slots symmetrically along the arms of a traditional CPW-fed slot dipole, achieving a much wider bandwidth. The middle band was realized by the fundamental mode of the slot dipole. To obtain the lower band, two identical inverted-L-shaped open-ended slots were symmetrically etched in the ground plane. A prototype was fabricated and measured, showing that tri-band operation with 10-dB return loss bandwidths of 150 MHz from 2.375 to 2.525 GHz, 725 MHz from 3.075 to 3.8 GHz, and 1.9 GHz from 5.0 to 6.9 GHz has been achieved. Details of the antenna design as well as the measured and simulated results are presented and discussed.
E1B-55K mediated regulation of RNF4 STUbL promotes HAdV gene expression.
Müncheberg, Sarah; Hay, Ron T; Ip, Wing H; Meyer, Tina; Weiß, Christina; Brenke, Jara; Masser, Sawinee; Hadian, Kamyar; Dobner, Thomas; Schreiner, Sabrina
2018-04-25
HAdV E1B-55K is a multifunctional regulator of productive viral replication and oncogenic transformation in non-permissive mammalian cells. These functions depend on E1B-55K's posttranslational modification with the SUMO protein and its binding to HAdV E4orf6. Both early viral proteins recruit specific host factors to form an E3 Ubiquitin ligase complex that targets antiviral host substrates for proteasomal degradation. Recently, we reported that the PML-NB-associated factor Daxx represses efficient HAdV productive infection and is proteasomally degraded via a SUMO-E1B-55K-dependent, E4orf6-independent pathway, the details of which remained to be established.RNF4, a cellular SUMO-targeted Ubiquitin ligase (STUbL), induces ubiquitinylation of specific SUMOylated proteins and plays an essential role during DNA repair. Here, we show that E1B-55K recruits RNF4 to the insoluble nuclear matrix fraction of the infected cell to support RNF4/Daxx association, promoting Daxx PTM, and thus inhibiting this antiviral factor. Removing RNF4 from infected cells using RNAi resulted in blocking the proper establishment of viral replication centers and significantly diminished viral gene expression. These results provide a model for how HAdV antagonize the antiviral host responses by exploiting the functional capacity of cellular STUbLs. Thus, RNF4 and its STUbL function represent a positive factor during lytic infection and a novel candidate for future therapeutic antiviral intervention strategies. IMPORTANCE Daxx is a PML-NB-associated transcription factor, which was recently shown to repress efficient HAdV productive infection. To counteract this antiviral measurement during infection, Daxx is degraded via a novel pathway including viral E1B-55K and host proteasomes. This virus-mediated degradation is independent of the classical HAdV E3 Ubiquitin ligase complex, which is essential during viral infection to target other host antiviral substrates. To maintain productive viral life
Closed String Tachyons, AdS/CFT, and QCD
International Nuclear Information System (INIS)
Silverstein, Eva M
2001-01-01
We find that tachyonic orbifold examples of AdS/CFT have corresponding instabilities at small radius, and can decay to more generic gauge theories. We do this by computing a destabilizing Coleman-Weinberg effective potential for twisted operators of the corresponding quiver gauge theories, generalizing calculations of Tseytlin and Zarembo and interpreting them in terms of the large-N behavior of twisted-sector modes. The dynamically generated potential involves double-trace operators, which affect large-N correlators involving twisted fields but not those involving only untwisted fields, in line with large-N inheritance arguments. We point out a simple reason that no such small radius instability exists in gauge theories arising from freely acting orbifolds, which are tachyon-free at large radius. When an instability is present, twisted gauge theory operators with the quantum numbers of the large-radius tachyons acquire VEVs, leaving a gauge theory with fewer degrees of freedom in the infrared, analogous to but less extreme than ''decays to nothing'' studied in other systems with broken supersymmetry. In some cases one is left with pure glue QCD plus decoupled matter and U(1) factors in the IR, which we thus conjecture is described by the corresponding (possibly strongly coupled) endpoint of tachyon condensation in the M/String-theory dual
Comments on Cosmic Censorship in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Hubeny, V.
2004-04-06
Recently Hertog, Horowitz, and Maeda (HHM) (hep-th/0310054) have proposed that cosmic censorship can be violated in the AdS/CFT context. They argue that for certain initial data there is insufficient energy available to make a black hole whose horizon is big enough to cloak the singularity that forms. We have investigated this proposal in the models HHM discuss and have thus far been unable to find initial data that provably satisfy this criterion, despite our development of an improved lower bound on the size of the singular region. This is consistent with recent numerical results (hep-th/0402109). For certain initial data, the energies of our configurations are not far above the lower bound on the requisite black hole mass, and so it is possible that in the exact time development naked singularities do form. We go on to argue that the finite radius cut-off AdS5 situation discussed by HHM displays instabilities when the full 10D theory is considered. We propose an AdS3 example that may well be free of this instability.
Comments on Cosmic Censorship in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Hubeny, Veronika E.; Liu, Xiao; Rangamani, Mukund; Shenker, Stephen
2004-03-21
Recently Hertog, Horowitz, and Maeda (HHM) (hep-th/0310054) have proposed that cosmic censorship can be violated in the AdS/CFT context. They argue that for certain initial data there is insufficient energy available to make a black hole whose horizon is big enough to cloak the singularity that forms. We have investigated this proposal in the models HHM discuss and have thus far been unable to find initial data that provably satisfy this criterion, despite our development of an improved lower bound on the size of the singular region. This is consistent with recent numerical results (hep-th/0402109). For certain initial data, the energies of our configurations are not far above the lower bound on the requisite black hole mass, and so it is possible that in the exact time development naked singularities do form. We go on to argue that the finite radius cut-off AdS_5 situation discussed by HHM displays instabilities when the full 10D theory is considered. We propose an AdS_3 example that may well be free of this instability.
Integrability and the AdS/CFT correspondence
International Nuclear Information System (INIS)
Serban, Didina
2011-01-01
The description of gauge theories at strong coupling is one of the long-standing problems in theoretical physics. The idea of a relation between strongly coupled gauge theories and string theory was pioneered by 't Hooft, Wilson and Polyakov. A decade ago, Maldacena made this relation explicit by conjecturing the exact equivalence of a conformally invariant theory in four dimensions, the maximally supersymmetric Yang-Mills theory, with string theory in the AdS 5 x S 5 background. Other examples of correspondence between a conformally invariant theory and string theory in an AdS background were discovered recently. The comparison of the two sides of the correspondence requires the use of non-perturbative methods. The discovery of integrable structures in gauge theory and string theory led to the conjecture that the two theories are integrable for any value of the coupling constant and that they share the same integrable structure defined non-perturbatively. The last 8 years brought remarkable progress in identifying this solvable model and in explicitly solving the problem of computing the spectrum of conformal dimensions of the theory. The progress came from the identification of the dilatation operator with an integrable spin chain and from the study of the string sigma model. In this review, I present the evolution of the concept of integrability in the framework of the AdS/CFT correspondence and the main results obtained using this approach. (review)
Closed String Tachyons, AdS/CFT, and QCD
Energy Technology Data Exchange (ETDEWEB)
Silverstein, Eva M
2001-07-25
We find that tachyonic orbifold examples of AdS/CFT have corresponding instabilities at small radius, and can decay to more generic gauge theories. We do this by computing a destabilizing Coleman-Weinberg effective potential for twisted operators of the corresponding quiver gauge theories, generalizing calculations of Tseytlin and Zarembo and interpreting them in terms of the large-N behavior of twisted-sector modes. The dynamically generated potential involves double-trace operators, which affect large-N correlators involving twisted fields but not those involving only untwisted fields, in line with large-N inheritance arguments. We point out a simple reason that no such small radius instability exists in gauge theories arising from freely acting orbifolds, which are tachyon-free at large radius. When an instability is present, twisted gauge theory operators with the quantum numbers of the large-radius tachyons acquire VEVs, leaving a gauge theory with fewer degrees of freedom in the infrared, analogous to but less extreme than ''decays to nothing'' studied in other systems with broken supersymmetry. In some cases one is left with pure glue QCD plus decoupled matter and U(1) factors in the IR, which we thus conjecture is described by the corresponding (possibly strongly coupled) endpoint of tachyon condensation in the M/String-theory dual.
Comments on cosmic censorship in AdS/CFT
International Nuclear Information System (INIS)
Hubeny, Veronika E.; Shenker, Stephen; Liu Xiao; Rangamani, Mukund
2004-01-01
Recently Hertog, Horowitz, and Maeda (HHM) have proposed that cosmic censorship can be violated in the AdS/CFT context. They argue that for certain initial data there is insufficient energy available to make a black hole whose horizon is big enough to cloak the singularity that forms. We have investigated this proposal in the models HHM discuss and have thus far been unable to find initial data that provably satisfy this criterion, despite our development of an improved lower bound on the size of the singular region. This is consistent with recent numerical results. For certain initial data, the energies of our configurations are not far above the lower bound on the requisite black hole mass, and so it is possible that in the exact time development naked singularities do form. We go on to argue that the finite radius cut-off AdS 5 situation discussed by HHM displays instabilities when the full 10D theory is considered. We propose an AdS 3 example that may well be free of this instability. (author)
Comments on cosmic censorship in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Hubeny, Veronika E. [Department of Physics, Stanford University, Stanford, CA 94305 (United States)]. E-mail: veronika@itp.stanford.edu; Shenker, Stephen [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Liu Xiao [Department of Physics, Stanford University, Stanford, CA 94305 (United States); SLAC, Stanford University, Stanford, CA 94309 (United States); Rangamani, Mukund [Department of Physics, University of California, Berkeley, CA 94720 (United States); Theoretical Physics Group, LBNL, Berkeley, CA 94720 (United States)
2004-12-01
Recently Hertog, Horowitz, and Maeda (HHM) have proposed that cosmic censorship can be violated in the AdS/CFT context. They argue that for certain initial data there is insufficient energy available to make a black hole whose horizon is big enough to cloak the singularity that forms. We have investigated this proposal in the models HHM discuss and have thus far been unable to find initial data that provably satisfy this criterion, despite our development of an improved lower bound on the size of the singular region. This is consistent with recent numerical results. For certain initial data, the energies of our configurations are not far above the lower bound on the requisite black hole mass, and so it is possible that in the exact time development naked singularities do form. We go on to argue that the finite radius cut-off AdS{sub 5} situation discussed by HHM displays instabilities when the full 10D theory is considered. We propose an AdS{sub 3} example that may well be free of this instability. (author)
Multi-trace deformations in AdS/CFT. Exploring the vacuum structure of the deformed CFT
Energy Technology Data Exchange (ETDEWEB)
Papadimitriou, I. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[Center for Mathematical Physics, Hamburg (Germany)
2007-03-15
We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to 'mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying 'mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of 'mixed' boundary conditions. (orig.)
Multi-trace deformations in AdS/CFT. Exploring the vacuum structure of the deformed CFT
International Nuclear Information System (INIS)
Papadimitriou, I.
2007-03-01
We present a general and systematic treatment of multi-trace deformations in the AdS/CFT correspondence in the large N limit, pointing out and clarifying subtleties relating to the formulation of the boundary value problem on a conformal boundary. We then apply this method to study multi-trace deformations in the presence of a scalar VEV, which requires the coupling to gravity to be taken into account. We show that supergravity solutions subject to 'mixed' boundary conditions are in one-to-one correspondence with critical points of the holographic effective action of the dual theory in the presence of a multi-trace deformation, and we find a number of new exact analytic solutions involving a minimally or conformally coupled scalar field satisfying 'mixed' boundary conditions. These include the generalization to any dimension of the instanton solution recently found in hep-th/0611315. Finally, we provide a systematic method for computing the holographic effective action in the presence of a multi-trace deformation in a derivative expansion away from the conformal vacuum using Hamilton-Jacobi theory. Requiring that this effective action exists and is bounded from below reproduces recent results on the stability of the AdS vacuum in the presence of 'mixed' boundary conditions. (orig.)
Full Scale Reinforced Concrete Beam-Column Joints Strengthened with Steel Reinforced Polymer Systems
Directory of Open Access Journals (Sweden)
Alessandro De Vita
2017-07-01
Full Text Available This paper presents the results of an experimental campaign performed at the Laboratory of Materials and Structural Testing of the University of Salerno (Italy in order to investigate the seismic performance of reinforced concrete (RC beam-column joints strengthened with steel reinforced polymer (SRP systems. With the aim to represent typical façade frames’ beam-column subassemblies found in existing RC buildings, specimens were provided with two short beam stubs orthogonal to the main beam and were designed with inadequate seismic details. Five members were strengthened by using two different SRP layouts while the remaining ones were used as benchmarks. Once damaged, two specimens were also repaired, retrofitted with SRP, and subjected to cyclic test again. The results of cyclic tests performed on SRP strengthened joints are examined through a comparison with the outcomes of the previous experimental program including companion specimens not provided with transverse beam stubs and strengthened by carbon fiber-reinforced polymer (CFRP systems. In particular, both qualitative and quantitative considerations about the influence of the confining effect provided by the secondary beams on the joint response, the suitability of all the adopted strengthening solutions (SRP/CFRP systems, the performances and the failure modes experienced in the several cases studied are provided.
Full Scale RC Beam-Column Joints Strengthened with Steel Reinforced Polymer Systems
De Vita, Alessandro; Napoli, Annalisa; Realfonzo, Roberto
2017-07-01
This paper presents the results of an experimental campaign performed at the Laboratory of Materials and Structural Testing of the University of Salerno (Italy) in order to investigate the seismic performance of RC beam-column joints strengthened with Steel Reinforced Polymer (SRP) systems. With the aim to represent typical façade frames’ beam-column subassemblies found in existing RC buildings, specimens were provided with two short beam stubs orthogonal to the main beam and were designed with inadequate seismic details. Five members were strengthened by using two different SRP layouts while the remaining ones were used as benchmarks. Once damaged, two specimens were also repaired, retrofitted with SRP and subjected to cyclic test again. The results of cyclic tests performed on SRP strengthened joints are examined through a comparison with the outcomes of the previous experimental program including companion specimens not provided with transverse beam stubs and strengthened by Carbon Fiber Reinforced Polymer (CFRP) systems. In particular, both qualitative and quantitative considerations about the influence of the confining effect provided by the secondary beams on the joint response, the suitability of all the adopted strengthening solutions (SRP/CFRP systems), the performances and the failure modes experienced in the several cases studied are provided.
Bogoliubov coefficients for the twist operator in the D1D5 CFT
Directory of Open Access Journals (Sweden)
Zaq Carson
2014-12-01
Full Text Available The D1D5 CFT is a holographic dual of a near-extremal black hole in string theory. The interaction in this theory involves a twist operator which joins together different copies of a free CFT. Given a large number of D1 and D5 branes, the effective length of the circle on which the CFT lives is very large. We develop a technique to study the effect of the twist operator in the limit where the wavelengths of excitations are short compared to this effective length, which we call the ‘continuum limit’. The method uses Bogoliubov coefficients to compute the effect of the twist operator in this limit. For bosonic fields, we use the method to reproduce recent results describing the effect of the twist operator when it links together CFT copies with windings M and N, producing a copy of winding M+N. We also comment on possible generalizations of our results. The methods developed here may help in understanding the twist interaction at higher orders. This in turn should provide insight into the thermalization process in the D1D5 CFT, which gives a holographic description of black hole formation.
Super-entropic black holes and the Kerr-CFT correspondence
Energy Technology Data Exchange (ETDEWEB)
Sinamuli, Musema [Department of Physics and Astronomy, University of Waterloo,200 University Ave., Waterloo, Ontario N2L 3G1 (Canada); Perimeter Institute for Theoretical Physics,31 Caroline St., Waterloo, Ontario, N2L 2Y5 (Canada); Mann, Robert B. [Department of Physics and Astronomy, University of Waterloo,200 University Ave., Waterloo, Ontario N2L 3G1 (Canada)
2016-08-24
We demonstrate that Kerr-CFT duality can be extended to super-entropic black holes, which have non-compact horizons with finite area. We demonstrate that this duality is robust insofar as the ultra-spinning limit of a Kerr-AdS black hole (which yields the super-entropic class) commutes with the near-horizon limit (which yields the Kerr-CFT duality). Consequently the Bekenstein-Hawking and the CFT entropies are equivalent. We show that the duality holds for both singly-spinning super-entropic black holes in 4 dimensions and for doubly-spinning super-entropic black holes of gauged supergravity in 5 dimensions. In both cases we obtain not only the expected left/right temperatures, but also temperatures associated with electric charge and with a new thermodynamic parameter specific to super-entropic black holes.
Super-entropic black holes and the Kerr-CFT correspondence
International Nuclear Information System (INIS)
Sinamuli, Musema; Mann, Robert B.
2016-01-01
We demonstrate that Kerr-CFT duality can be extended to super-entropic black holes, which have non-compact horizons with finite area. We demonstrate that this duality is robust insofar as the ultra-spinning limit of a Kerr-AdS black hole (which yields the super-entropic class) commutes with the near-horizon limit (which yields the Kerr-CFT duality). Consequently the Bekenstein-Hawking and the CFT entropies are equivalent. We show that the duality holds for both singly-spinning super-entropic black holes in 4 dimensions and for doubly-spinning super-entropic black holes of gauged supergravity in 5 dimensions. In both cases we obtain not only the expected left/right temperatures, but also temperatures associated with electric charge and with a new thermodynamic parameter specific to super-entropic black holes.
International Nuclear Information System (INIS)
Hoffmann, L.; Leonhardt, T.; Mesref, L.; Ruehl, W.
2001-01-01
We discuss the concept of composite fields in flat CFT as well as in the context of AdS/CFT. Furthermore we show how to represent Green functions using generalized hypergeometric functions and apply these techniques to four-point functions. Finally we prove an identity of U(1) Y symmetry for four-point functions
Hoffmann, L.; Leonhardt, T.; Mesref, L.; Rühl, W.
2001-09-01
We discuss the concept of composite fields in flat CFT as well as in the context of AdS/CFT. Furthermore we show how to represent Green functions using generalized hypergeometric functions and apply these techniques to four-point functions. Finally we prove an identity of U(1)Y symmetry for four-point functions.
Castro, Jorge
2017-07-11
This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns.
Analog geometry in an expanding fluid from AdS/CFT perspective
Bilić, Neven; Domazet, Silvije; Tolić, Dijana
2015-04-01
The dynamics of an expanding hadron fluid at temperatures below the chiral transition is studied in the framework of AdS/CFT correspondence. We establish a correspondence between the asymptotic AdS geometry in the 4 + 1 dimensional bulk with the analog spacetime geometry on its 3 + 1 dimensional boundary with the background fluid undergoing a spherical Bjorken type expansion. The analog metric tensor on the boundary depends locally on the soft pion dispersion relation and the four-velocity of the fluid. The AdS/CFT correspondence provides a relation between the pion velocity and the critical temperature of the chiral phase transition.
AdS/CFT correspondence, quasinormal modes, and thermal correlators in N=4 SYM
Nunez, Alvaro; Starinets, Andrei O.
2003-01-01
We use the Lorentzian AdS/CFT prescription to find the poles of the retarded thermal Green's functions of ${\\cal N=4}$ SU(N) SYM theory in the limit of large N and large 't Hooft coupling. In the process, we propose a natural definition for quasinormal modes in an asymptotically AdS spacetime, with boundary conditions dictated by the AdS/CFT correspondence. The corresponding frequencies determine the dispersion laws for the quasiparticle excitations in the dual finite-temperature gauge theory...
A comment on the infra-red problem in the AdS/CFT correspondence
International Nuclear Information System (INIS)
Gottschalk, Hanno; Thaler, Horst
2008-01-01
In this note we report on some recent progress in proving the AdS/CFT correspondence for quantum fields using rigorously defined Euclidean path integrals. We also comment on the infra-red problem in the AdS/CFT correspondence and argue that it is different from the usual IR problem in constructive quantum field theory. To illustrate this, a triviality proof based on hypercontractivity estimates is given for the case of an ultraviolet regularized potential of type: φ 4 :. We also give a brief discussion on possible renormalization strategies and the specific problems that arise in this context. (orig.)
A comment on the infra-red problem in the AdS/CFT correspondence
Energy Technology Data Exchange (ETDEWEB)
Gottschalk, Hanno; Thaler, Horst
2008-03-15
In this note we report on some recent progress in proving the AdS/CFT correspondence for quantum fields using rigorously defined Euclidean path integrals. We also comment on the infra-red problem in the AdS/CFT correspondence and argue that it is different from the usual IR problem in constructive quantum field theory. To illustrate this, a triviality proof based on hypercontractivity estimates is given for the case of an ultraviolet regularized potential of type: {phi}{sup 4}:. We also give a brief discussion on possible renormalization strategies and the specific problems that arise in this context. (orig.)
Test of the local form of higher-spin equations via AdS/CFT
Directory of Open Access Journals (Sweden)
V.E. Didenko
2017-12-01
Full Text Available The local form of higher-spin equations found recently to the second order [1] is shown to properly reproduce the anticipated AdS/CFT correlators for appropriate boundary conditions. It is argued that consistent AdS/CFT holography for the parity-broken boundary models needs a nontrivial modification of the bosonic truncation of the original higher-spin theory with the doubled number of fields, as well as a nonlinear deformation of the boundary conditions in the higher orders.
CFT and Logarithmic Corrections to the Black Hole Entropy Product Formula
Directory of Open Access Journals (Sweden)
Parthapratim Pradhan
2017-01-01
Full Text Available We examine the logarithmic corrections to the black hole (BH entropy product formula of outer horizon and inner horizon by taking into account the effects of statistical quantum fluctuations around the thermal equilibrium and via conformal field theory (CFT. We argue that, in logarithmic corrections to the BH entropy product formula when calculated using CFT and taking into account the effects of quantum fluctuations around the thermal equilibrium, the formula should not be universal and it also should not be quantized. These results have been explicitly checked by giving several examples.
( Anogeissus leiocarpus ) timber columns
African Journals Online (AJOL)
A procedure for designing axially loaded Ayin (Anogeissus leiocarpus) wood column or strut has been investigated. Instead of the usual categorization of columns into short, intermediate and slender according to the value of slenderness ratio, a continuous column formula representing the three categories was derived.
Majors, Ronald E.; And Others
1984-01-01
Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…
Directory of Open Access Journals (Sweden)
Dongbo Zhang
2016-08-01
Full Text Available In this work, we applied a robust and fully air-coupled method to investigate the propagation of the lowest-order antisymmetric Lamb (A0 mode in both a stubbed and an air-drilled phononic-crystal (PC plate. By measuring simply the radiative acoustic waves of A0 mode close to the plate surface, we observed the band gaps for the stubbed PC plate caused by either the local resonance or the Bragg scattering, in frequency ranges in good agreement with theoretical predictions. We measured then the complete band gap of A0 mode for the air-drilled PC plate, in good agreement with the band structures. Finally, we compared the measurements made using the air-coupled method with those obtained by the laser ultrasonic technique.
Chuluunbaatar, Z; Wang, C; Kim, N Y
2014-01-01
This paper reports a compact bandpass filter with improved skirt selectivity using integrated passive device fabrication technology on a GaAs substrate. The structure of the filter consists of electromagnetically coupled meandered-line symmetric stepped-impedance resonators. The strength of the coupling between the resonators is enhanced by using a meandered-line stub-load inside the resonators to improve the selectivity and miniaturize the size of the filter. In addition, the center frequency of the filter can be flexibly controlled by varying degrees of the capacitive coupling between resonator and stub-load. To verify the proposed concept, a protocol bandpass filter with center frequency of 6.53 GHz was designed, fabricated, and measured, with a return loss and insertion loss of 39.1 dB and 1.63 dB.
Directory of Open Access Journals (Sweden)
Z. Chuluunbaatar
2014-01-01
Full Text Available This paper reports a compact bandpass filter with improved skirt selectivity using integrated passive device fabrication technology on a GaAs substrate. The structure of the filter consists of electromagnetically coupled meandered-line symmetric stepped-impedance resonators. The strength of the coupling between the resonators is enhanced by using a meandered-line stub-load inside the resonators to improve the selectivity and miniaturize the size of the filter. In addition, the center frequency of the filter can be flexibly controlled by varying degrees of the capacitive coupling between resonator and stub-load. To verify the proposed concept, a protocol bandpass filter with center frequency of 6.53 GHz was designed, fabricated, and measured, with a return loss and insertion loss of 39.1 dB and 1.63 dB.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Dongbo; Zhao, Jinfeng, E-mail: jinfeng.zhao@tongji.edu.cn; Li, Libing; Pan, Yongdong; Zhong, Zheng [School of Aerospace Engineering and Applied Mechanics, Tongji University, 100 Zhangwu Road, 200092, Shanghai (China); Bonello, Bernard [CNRS, UMR 7588, Institut des NanoSciences de Paris, F-75005, Paris (France); Wei, Jianxin [State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, 18 Xuefu Road, 102249, Pekin (China)
2016-08-15
In this work, we applied a robust and fully air-coupled method to investigate the propagation of the lowest-order antisymmetric Lamb (A{sub 0}) mode in both a stubbed and an air-drilled phononic-crystal (PC) plate. By measuring simply the radiative acoustic waves of A{sub 0} mode close to the plate surface, we observed the band gaps for the stubbed PC plate caused by either the local resonance or the Bragg scattering, in frequency ranges in good agreement with theoretical predictions. We measured then the complete band gap of A{sub 0} mode for the air-drilled PC plate, in good agreement with the band structures. Finally, we compared the measurements made using the air-coupled method with those obtained by the laser ultrasonic technique.
AdS boundary conditions and the Topologically Massive Gravity/CFT correspondence
Skenderis, K.; Taylor, M.; van Rees, B.C.
2009-01-01
The AdS/CFT correspondence provides a new perspective on recurrent questions in General Relativity such as the allowed boundary conditions at infinity and the definition of gravitational conserved charges. Here we review the main insights obtained in this direction over the last decade and apply the
Propagation of few cycle optical pulses in marginal Fermi liquid and ADS/CFT correspondence
Energy Technology Data Exchange (ETDEWEB)
Konobeeva, N.N., E-mail: yana_nn@inbox.ru [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Belonenko, M.B. [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Volgograd Institute of Business, Uzhno-ukrainskaya str., Volgograd 400048 (Russian Federation)
2015-12-01
Absract: The paper considers features of few cycle optical pulse propagation in marginal Fermi liquid. The Green functions whose poles are responsible for the dispersion law excitation states of the liquid have been derived within the framework of ADS/CFT correspondence. Marginal Fermi liquid parameters influence on the pulse shape was defined.
A non-supersymmetric deformation of the AdS/CFT correspondence
International Nuclear Information System (INIS)
Babington, James; Crooks, David E.; Evans, Nick
2003-01-01
We deform the AdS/CFT Correspondence by the inclusion of a non-supersymmetric scalar mass operator. We discuss the behaviour of the dual 5 dimensional supergravity field then lift the full solution to 10 dimensions. Brane probing the resulting background reveals a potential consistent with the operator we wished to insert. (author)
Propagation of few cycle optical pulses in marginal Fermi liquid and ADS/CFT correspondence
International Nuclear Information System (INIS)
Konobeeva, N.N.; Belonenko, M.B.
2015-01-01
Absract: The paper considers features of few cycle optical pulse propagation in marginal Fermi liquid. The Green functions whose poles are responsible for the dispersion law excitation states of the liquid have been derived within the framework of ADS/CFT correspondence. Marginal Fermi liquid parameters influence on the pulse shape was defined.
International Nuclear Information System (INIS)
Huff, Thomas
2010-01-01
Small Column Ion Exchange (SCIX) leverages a suite of technologies developed by DOE across the complex to achieve lifecycle savings. Technologies are applicable to multiple sites. Early testing supported multiple sites. Balance of SRS SCIX testing supports SRS deployment. A forma Systems Engineering Evaluation (SEE) was performed and selected Small Column Ion Exchange columns containing Crystalline Silicotitanate (CST) in a 2-column lead/lag configuration. SEE considered use of Spherical Resorcinol-Formaldehyde (sRF). Advantages of approach at SRS include: (1) no new buildings, (2) low volume of Cs waste in solid form compared to aqueous strip effluent; and availability of downstream processing facilities for immediate processing of spent resin.
An alternative path to the boundary: The CFT as the Fourier space of AdS
Tolfree, Ian M.
2009-12-01
In this thesis we shed new light on the conjectured duality between an n + 1 dimensional theory of gravity in anti de Sitter space (AdS) and an n dimensional conformal field theory (CFT) by showing that the CFT can be interpreted as the Fourier space of AdS. We then make use of this to gain insight into the nature of black hole entropy. In the first part of this thesis, we give an introduction to the ideas of and review the basics of the AdS/CFT. In the next section we make use of well known integral geometry techniques to derive the Fourier transformation of a function on AdS and see it is a function with compact support on the boundary. Comparing this to the literature, we find that the Green's functions from the literature are actually the Fourier weights of the transformation and that the boundary values of fields appearing in the correspondence are the Fourier coefficients of the transformation. One is thus left to interpret the CFT as the quantized version of a classical theory in AdS and the dual operator as the Fourier coefficients. Group theoretic considerations are discussed in relation to the transformation and its potential use in constructing QCD like theories. In the last section, we then build upon this to study the BTZ black hole. Named after its authors, Banados, Teitelboim and Zanelli, the BTZ black hole is a three dimensional (two space plus one time dimension) black hole in anti de Sitter space. Following standard procedures for modifying Fourier Transformations to accommodate quotient spaces we arrive at a mapping in a black hole background consistent with known results that yields the exact micro-states of a scalar field in a black hole background. We find that the micro-states are the Fourier coefficients on the boundary, which transform under the principal series representation of SL(2, R). Using the knowledge of how to represent a bulk scalar field in the CFT, and knowing how a black hole interacts with a scalar field, we deduce the
Chae, Changyu; Walters, Matthew J; Holman, Matthew R
2017-07-01
We investigated the differences in TNCO (tar, nicotine, and carbon monoxide) smoke yields generated under the International Organization of Standardization (ISO) and Federal Trade Commission (FTC) Cambridge Filter Test (CFT) smoking regimens. Twenty-nine commercial cigarette products from the US marketplace were acquired in 2015 and tested by measuring the TNCO smoke yields generated under these 2 nonintense smoking regimens. Data obtained demonstrated a linear relationship between the TNCO yields produced under the 2 smoking regimens (R 2 > 0.99). TNCO yields produced by each product were higher under the CFT smoking regimen than the ISO smoking regimen. We found that tar, nicotine, and carbon monoxide yields were consistently 10% to 13% higher under the CFT smoking regimen than under the ISO smoking regimen. This strong correlation indicates that the 2 smoking regimens can be used to apply a correlation correction to CFT TNCO data and allow its comparison to ISO TNCO data in tobacco product marketing applications.
Holmes, Jon L.
1999-05-01
The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad
Logarithmic sℓ-hat (2) CFT models from Nichols algebras: I
International Nuclear Information System (INIS)
Semikhatov, A M; Tipunin, I Yu
2013-01-01
We construct chiral algebras that centralize rank-2 Nichols algebras with at least one fermionic generator. This gives ‘logarithmic’ W-algebra extensions of a fractional-level sℓ-hat (2) algebra. We discuss crucial aspects of the emerging general relation between Nichols algebras and logarithmic conformal field theory (CFT) models: (i) the extra input, beyond the Nichols algebra proper, needed to uniquely specify a conformal model; (ii) a relation between the CFT counterparts of Nichols algebras connected by Weyl groupoid maps; and (iii) the common double bosonization U(X) of such Nichols algebras. For an extended chiral algebra, candidates for its simple modules that are counterparts of the U(X) simple modules are proposed, as a first step toward a functorial relation between U(X) and W-algebra representation categories. (paper)
Precursors, gauge invariance, and quantum error correction in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Freivogel, Ben; Jefferson, Robert A.; Kabir, Laurens [ITFA and GRAPPA, Universiteit van Amsterdam,Science Park 904, Amsterdam (Netherlands)
2016-04-19
A puzzling aspect of the AdS/CFT correspondence is that a single bulk operator can be mapped to multiple different boundary operators, or precursors. By improving upon a recent model of Mintun, Polchinski, and Rosenhaus, we demonstrate explicitly how this ambiguity arises in a simple model of the field theory. In particular, we show how gauge invariance in the boundary theory manifests as a freedom in the smearing function used in the bulk-boundary mapping, and explicitly show how this freedom can be used to localize the precursor in different spatial regions. We also show how the ambiguity can be understood in terms of quantum error correction, by appealing to the entanglement present in the CFT. The concordance of these two approaches suggests that gauge invariance and entanglement in the boundary field theory are intimately connected to the reconstruction of local operators in the dual spacetime.
2D CFT blocks for the 4D class S{sub k} theories
Energy Technology Data Exchange (ETDEWEB)
Mitev, Vladimir [Mainz Univ. (Germany). Inst. fuer Physik; Pomoni, Elli [DESY, Hamburg (Germany). Theory Group
2017-03-15
This is the first in a series of papers on the search for the 2D CFT description of a large class of 4D N=1 gauge theories. Here, we identify the 2D CFT symmetry algebra and its representations, namely the conformal blocks of the Virasoro/W-algebra, that underlie the 2D theory and reproduce the Seiberg-Witten curves of the N=1 gauge theories. We find that the blocks corresponding to the SU(N) S{sub k} gauge theories involve fields in certain non-unitary representations of the W{sub kN} algebra. These conformal blocks give a prediction for the instanton partition functions of the 4D N=1 SCFTs of class S{sub k}.
2D CFT blocks for the 4D class Sk theories
International Nuclear Information System (INIS)
Mitev, Vladimir; Pomoni, Elli
2017-03-01
This is the first in a series of papers on the search for the 2D CFT description of a large class of 4D N=1 gauge theories. Here, we identify the 2D CFT symmetry algebra and its representations, namely the conformal blocks of the Virasoro/W-algebra, that underlie the 2D theory and reproduce the Seiberg-Witten curves of the N=1 gauge theories. We find that the blocks corresponding to the SU(N) S k gauge theories involve fields in certain non-unitary representations of the W kN algebra. These conformal blocks give a prediction for the instanton partition functions of the 4D N=1 SCFTs of class S k .
Hawking radiation and quantum anomaly in AdS2/CFT1 correspondence
International Nuclear Information System (INIS)
Morita, Takeshi
2009-01-01
In order to understand a boundary description of Hawking radiation in the AdS/CFT correspondence, we investigate the trace anomaly method in AdS 2 space. In this method, Hawking radiation is derived from the trace anomaly of the energy-momentum tensor in the bulk. We find a correspondence between the energy-momentum tensor and a composite operator in CFT 1 and understand the anomalous properties of the energy-momentum tensor in terms of this composite operator. By using this correspondence, we reproduce Hawking radiation from the boundary description. In addition, we find a correspondence between higher-spin currents in the bulk and composite operators in the boundary.
Comparing AdS/CFT dipole model to HERA F2 data
International Nuclear Information System (INIS)
LU Zhun
2010-01-01
We apply an AdS/CFT-inspired color-dipole model which contains only three free parameters to describe the HERA data for the inclusive structure function F 2 at small Bjorken-x and virtuality. We found that the saturation scale in our AdS/CFT-based parameterization varies in the range of 1-3 GeV becoming independent of energy/Bjorken-x at very small x. This leads to the prediction of x-independence of the structure functions at very small x. With the fitted parameters in our model, the predictions for F 2 , longitudinal structure function, charm structure function and total photo-production cross-sections in the kinematic regions of future experiments can be given. (authors)
Discontinuity relations for the AdS{sub 4}/CFT{sub 3} correspondence
Energy Technology Data Exchange (ETDEWEB)
Cavaglià, Andrea, E-mail: Cavaglia@to.infn.it [Centre for Mathematical Science, City University London, Northampton Square, London EC1V 0HB (United Kingdom); Dipartimento di Fisica and INFN, Università di Torino, Via P. Giuria 1, 10125 Torino (Italy); Fioravanti, Davide, E-mail: Fioravanti@bo.infn.it [INFN-Bologna and Dipartimento di Fisica e Astronomia, Università di Bologna, Via Irnerio 46, 40126 Bologna (Italy); Tateo, Roberto, E-mail: Tateo@to.infn.it [Dipartimento di Fisica and INFN, Università di Torino, Via P. Giuria 1, 10125 Torino (Italy)
2013-12-21
We study in detail the analytic properties of the Thermodynamic Bethe Ansatz (TBA) equations for the anomalous dimensions of composite operators in the planar limit of the 3D N=6 superconformal Chern–Simons gauge theory and derive functional relations for the jump discontinuities across the branch cuts in the complex rapidity plane. These relations encode the analytic structure of the Y functions and are extremely similar to the ones obtained for the previously-studied AdS{sub 5}/CFT{sub 4} case. Together with the Y-system and more basic analyticity conditions, they are completely equivalent to the TBA equations. We expect these results to be useful to derive alternative nonlinear integral equations for the AdS{sub 4}/CFT{sub 3} spectrum.
Vacuum states and the S matrix in dS/CFT
International Nuclear Information System (INIS)
Spradlin, Marcus; Volovich, Anastasia
2002-01-01
We propose a definition of dS/CFT correlation functions by equating them to S-matrix elements for scattering particles from I - to I + . In planar coordinates, which cover half of de Sitter space, we consider instead the S vector obtained by specifying a fixed state on the horizon. We construct the one-parameter family of de Sitter invariant vacuum states for a massive scalar field in these coordinates, and show that the vacuum obtained by analytic continuation from the sphere has no particles on the past horizon. We use this formalism to provide evidence that the one-parameter family of vacua corresponds to marginal deformations of the CFT by computing a three-point function
Real-time response in AdS/CFT with application to spinors
International Nuclear Information System (INIS)
Iqbal, N.; Liu, H.
2009-01-01
We discuss a simple derivation of the real-time AdS/CFT prescription as an analytic continuation of the corresponding problem in Euclidean signature. We then extend the formalism to spinor operators and apply it to the examples of real-time fermionic correlators in CFTs dual to pure AdS and the BTZ black hole. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
Instantons on D7 brane probes and AdS/CFT with flavour
International Nuclear Information System (INIS)
Apreda, R.; Erdmenger, J.; Grosse, J.; Evans, N.; Guralnik, Z.
2006-01-01
Recent work on adding flavour to the generalized AdS/CFT correspondence is reviewed. In particular, we consider instanton configurations on two coincident D7 brane probes. These are matched to the Higgs branch of the dual field theory. In AdS 5 x S 5 , the instanton generates a flow of the meson spectrum. For non-supersymmetric gravity backgrounds, the Higgs branch is lifted by a potential with non-trivial physical implications. (Abstract Copyright [2006], Wiley Periodicals, Inc.)
4D scattering amplitudes and asymptotic symmetries from 2D CFT
Cheung, Clifford; de la Fuente, Anton; Sundrum, Raman
2017-01-01
We reformulate the scattering amplitudes of 4D flat space gauge theory and gravity in the language of a 2D CFT on the celestial sphere. The resulting CFT structure exhibits an OPE constructed from 4D collinear singularities, as well as infinite-dimensional Kac-Moody and Virasoro algebras encoding the asymptotic symmetries of 4D flat space. We derive these results by recasting 4D dynamics in terms of a convenient foliation of flat space into 3D Euclidean AdS and Lorentzian dS geometries. Tree-level scattering amplitudes take the form of Witten diagrams for a continuum of (A)dS modes, which are in turn equivalent to CFT correlators via the (A)dS/CFT dictionary. The Ward identities for the 2D conserved currents are dual to 4D soft theorems, while the bulk-boundary propagators of massless (A)dS modes are superpositions of the leading and subleading Weinberg soft factors of gauge theory and gravity. In general, the massless (A)dS modes are 3D Chern-Simons gauge fields describing the soft, single helicity sectors of 4D gauge theory and gravity. Consistent with the topological nature of Chern-Simons theory, Aharonov-Bohm effects record the "tracks" of hard particles in the soft radiation, leading to a simple characterization of gauge and gravitational memories. Soft particle exchanges between hard processes define the Kac-Moody level and Virasoro central charge, which are thereby related to the 4D gauge coupling and gravitational strength in units of an infrared cutoff. Finally, we discuss a toy model for black hole horizons via a restriction to the Rindler region.
Distillation Column Flooding Predictor
Energy Technology Data Exchange (ETDEWEB)
George E. Dzyacky
2010-11-23
The Flooding Predictor™ is a patented advanced control technology proven in research at the Separations Research Program, University of Texas at Austin, to increase distillation column throughput by over 6%, while also increasing energy efficiency by 10%. The research was conducted under a U. S. Department of Energy Cooperative Agreement awarded to George Dzyacky of 2ndpoint, LLC. The Flooding Predictor™ works by detecting the incipient flood point and controlling the column closer to its actual hydraulic limit than historical practices have allowed. Further, the technology uses existing column instrumentation, meaning no additional refining infrastructure is required. Refiners often push distillation columns to maximize throughput, improve separation, or simply to achieve day-to-day optimization. Attempting to achieve such operating objectives is a tricky undertaking that can result in flooding. Operators and advanced control strategies alike rely on the conventional use of delta-pressure instrumentation to approximate the column’s approach to flood. But column delta-pressure is more an inference of the column’s approach to flood than it is an actual measurement of it. As a consequence, delta pressure limits are established conservatively in order to operate in a regime where the column is never expected to flood. As a result, there is much “left on the table” when operating in such a regime, i.e. the capacity difference between controlling the column to an upper delta-pressure limit and controlling it to the actual hydraulic limit. The Flooding Predictor™, an innovative pattern recognition technology, controls columns at their actual hydraulic limit, which research shows leads to a throughput increase of over 6%. Controlling closer to the hydraulic limit also permits operation in a sweet spot of increased energy-efficiency. In this region of increased column loading, the Flooding Predictor is able to exploit the benefits of higher liquid
Nuclear reactor control column
International Nuclear Information System (INIS)
Bachovchin, D.M.
1982-01-01
The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest crosssectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor
One-loop transition amplitudes in the D1D5 CFT
Energy Technology Data Exchange (ETDEWEB)
Carson, Zaq; Hampton, Shaun; Mathur, Samir D. [Department of Physics, The Ohio State University,191 West Woodruff Ave, Columbus, OH 43210 (United States)
2017-01-02
We consider the issue of thermalization in the D1D5 CFT. Thermalization is expected to correspond to the formation of a black hole in the dual gravity theory. We start from the orbifold point, where the theory is essentially free, and does not thermalize. In earlier work it was noted that there was no clear thermalization effect when the theory was deformed off the orbifold point to first order in the relevant twist perturbation. In this paper we consider the deformation to second order in the twist, where we do find effects that can cause thermalization of an initial perturbation. We consider a 1-loop process where two untwisted copies of the CFT are twisted to one copy and then again untwisted to two copies. We start with a single oscillator excitation on the initial CFT, and compute the effect of the two twists on this state. We find simple approximate expressions for the Bogoliubov coefficients and the behavior of the single oscillator excitation in the continuum limit, where the mode numbers involved are taken to be much larger than unity. We also prove a number of useful relationships valid for processes with an arbitrary number of twist insertions.
Stability of Horava-Lifshitz black holes in the context of AdS/CFT
International Nuclear Information System (INIS)
Ong, Yen Chin; Chen, Pisin
2011-01-01
The anti-de Sitter/conformal field theory (AdS/CFT) correspondence is a powerful tool that promises to provide new insights toward a full understanding of field theories under extreme conditions, including but not limited to quark-gluon plasma, Fermi liquid, and superconductor. In many such applications, one typically models the field theory with asymptotically AdS black holes. These black holes are subjected to stringy effects that might render them unstable. Horava-Lifshitz gravity, in which space and time undergo different transformations, has attracted attention due to its power-counting renormalizability. In terms of AdS/CFT correspondence, Horava-Lifshitz black holes might be useful to model holographic superconductors with Lifshitz scaling symmetry. It is thus interesting to study the stringy stability of Horava-Lifshitz black holes in the context of AdS/CFT. We find that uncharged topological black holes in λ=1 Horava-Lifshitz theory are nonperturbatively stable, unlike their counterparts in Einstein gravity, with the possible exceptions of negatively curved black holes with detailed balance parameter ε close to unity. Sufficiently charged flat black holes for ε close to unity, and sufficiently charged positively curved black holes with ε close to zero, are also unstable. The implication to the Horava-Lifshitz holographic superconductor is discussed.
From gravity to thermal gauge theories. The AdS/CFT correspondence
International Nuclear Information System (INIS)
Papantonopoulos, Eleftherios
2011-01-01
The AdS/CFT correspondence is a powerful tool in studying strongly coupled phenomena in gauge field theories, using results from a weakly coupled gravity background studied in the realm of string theory. AdS/CFT was first successfully applied to the study of phenomena such as the quark-gluon plasma produced in heavy ions collisions. Soon it was realized that its applicability can be extended, in a more phenomenological approach, to condensed matter systems and to systems described by fluid dynamics. The set of tutorial reviews in this volume is intended as an introduction to and survey of the principle of the AdS/CFT correspondence in its field/string theoretic formulation, its applicability to holographic QCD and to heavy ions collisions, and to give a first account of processes in fluid dynamics and condensed matter physics, which can be studied with the use of this principle. Written by leading researchers in the field and cast into the form of a high-level but approachable multi-author textbook, this volume will be of benefit to all postgraduate students, and newcomers from neighboring disciplines wishing to find a comprehensive guide for their future research. (orig.)
1-loop partition function in AdS{sub 3}/CFT{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Chen, Bin [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Collaborative Innovation Center of Quantum Matter,5 Yiheyuan Rd, Beijing 100871 (China); Center for High Energy Physics, Peking University,5 Yiheyuan Rd, Beijing 100871 (China); Wu, Jie-qiang [Department of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,5 Yiheyuan Rd, Beijing 100871 (China)
2015-12-16
The 1-loop partition function of the handlebody solutions in the AdS{sub 3} gravity have been derived some years ago using the heat kernel techniques and the method of images. In the semiclassical limit, such partition function should correspond to the order O(c{sup 0}) part in the partition function of dual conformal field theory(CFT) on the boundary Riemann surface. The higher genus partition function could be computed by the multi-point functions in the Riemann sphere via sewing prescription. In the large central charge limit, the CFT is effectively free in the sense that to the leading order of c the multi-point function is further simplified to be a summation over the products of two-point functions of single-particle states. Correspondingly in the bulk, the graviton is freely propagating without interaction. Furthermore the product of the two-point functions may define the links, each of which is in one-to-one correspondence with the conjugacy class of the Schottky group of the Riemann surface. Moreover, the value of a link is determined by the multiplier of the element in the conjugacy class. This allows us to reproduce exactly the gravitational 1-loop partition function. The proof can be generalized to the higher spin gravity and its dual CFT.
Scalar 3-point functions in CFT: renormalisation, beta functions and anomalies
Bzowski, Adam; McFadden, Paul; Skenderis, Kostas
2016-03-01
We present a comprehensive discussion of renormalisation of 3-point functions of scalar operators in conformal field theories in general dimension. We have previously shown that conformal symmetry uniquely determines the momentum-space 3-point functions in terms of certain integrals involving a product of three Bessel functions (triple- K integrals). The triple- K integrals diverge when the dimensions of operators satisfy certain relations and we discuss how to obtain renormalised 3-point functions in all cases. There are three different types of divergences: ultralocal, semilocal and nonlocal, and a given divergent triple- K integral may have any combination of them. Ultralocal divergences may be removed using local counterterms and this results in new conformal anomalies. Semilocal divergences may be removed by renormalising the sources, and this results in CFT correlators that satisfy Callan-Symanzik equations with beta functions. In the case of non-local divergences, it is the triple- K representation that is singular, not the 3-point function. Here, the CFT correlator is the coefficient of the leading nonlocal singularity, which satisfies all the expected conformal Ward identities. Such correlators exhibit enhanced symmetry: they are also invariant under dual conformal transformations where the momenta play the role of coordinates. When both anomalies and beta functions are present the correlators exhibit novel analytic structure containing products of logarithms of momenta. We illustrate our discussion with numerous examples, including free field realisations and AdS/CFT computations.
One-loop transition amplitudes in the D1D5 CFT
Carson, Zaq; Hampton, Shaun; Mathur, Samir D.
2017-01-01
We consider the issue of thermalization in the D1D5 CFT. Thermalization is expected to correspond to the formation of a black hole in the dual gravity theory. We start from the orbifold point, where the theory is essentially free, and does not thermalize. In earlier work it was noted that there was no clear thermalization effect when the theory was deformed off the orbifold point to first order in the relevant twist perturbation. In this paper we consider the deformation to second order in the twist, where we do find effects that can cause thermalization of an initial perturbation. We consider a 1-loop process where two untwisted copies of the CFT are twisted to one copy and then again untwisted to two copies. We start with a single oscillator excitation on the initial CFT, and compute the effect of the two twists on this state. We find simple approximate expressions for the Bogoliubov coefficients and the behavior of the single oscillator excitation in the continuum limit, where the mode numbers involved are taken to be much larger than unity. We also prove a number of useful relationships valid for processes with an arbitrary number of twist insertions.
Improvements in solvent extraction columns
International Nuclear Information System (INIS)
Aughwane, K.R.
1987-01-01
Solvent extraction columns are used in the reprocessing of irradiated nuclear fuel. For an effective reprocessing operation a solvent extraction column is required which is capable of distributing the feed over most of the column. The patent describes improvements in solvent extractions columns which allows the feed to be distributed over an increased length of column than was previously possible. (U.K.)
Targeting of SUMO substrates to a Cdc48-Ufd1-Npl4 segregase and STUbL pathway in fission yeast
DEFF Research Database (Denmark)
Køhler, Julie Bonne; Tammsalu, Triin; Jørgensen, Maria Louise Mønster
2015-01-01
48/p97-Ufd1-Npl4 facilitates this process. However, the extent to which the two pathways overlap, and how substrates are selected, remains unknown. Here we address these questions in fission yeast through proteome-wide analyses of SUMO modification sites. We identify over a thousand sumoylated...... lysines in a total of 468 proteins and quantify changes occurring in the SUMO modification status when the STUbL or Ufd1 pathways are compromised by mutations. The data suggest the coordinated processing of several classes of SUMO conjugates, many dynamically associated with centromeres or telomeres...
Habibi, M.; Rahmani, Y.; Bonn, D.; Ribe, N.M.
2010-01-01
Under appropriate conditions, a column of viscous liquid falling onto a rigid surface undergoes a buckling instability. Here we show experimentally and theoretically that liquid buckling exhibits a hitherto unsuspected complexity involving three different modes—viscous, gravitational, and
Deformed D1D5 CFT: A Holographic Probe of Quantum Gravity
Jardine, Ian Theodore
One of the big unsolved questions in gravity research is the black hole information problem. This problem, which pits the unitarity of quantum field theory against smooth classical spacetime, must have a solution in a complete theory of quantum gravity. This thesis will explore aspects of one approach to this problem in the context of string theory. The approach imagines black hole microstates as string theoretic objects. We look at a prototype system, the D1D5 system, and exploit holography to examine the dual conformal field theory (CFT). Specifically, we examine the CFT deformed from the free orbifold point, dual to a very stringy bulk, using a twisted operator that will take us towards the point with the supergravity description. The effects of twisted operators in the CFT are key to understanding physical processes such as emission and thermalization in black hole microstates. We will propose a component twist method for examining the effects of bare twist operators for higher twists in the continuum limit. Our method builds higher twists from simple 2-cycle twists, whose effects are known. We will find that, in this limit, the coefficients describing general states will follow a conjectured general functional form. We then explore the deformed CFT directly by examining operator mixing for untwisted operators. We will exploit the operator product expansion on the covering space, where twist operators of the orbifold are resolved. We use this to examine the mixing of a general supergravity operator, specifically examine the dilaton, and finish with the mixing of a non-supersymmetric candidate operator. We conjecture that this method could be extended to include twisted operators. We will also examine the mixing of the non-supersymmetric candidate operator by examining three point functions. To automate the lengthy and repetitive computations, we wrote a Mathematica package to compute correlation functions and OPEs in the D1D5 CFT. We will explain some of the
International Nuclear Information System (INIS)
Middleton, P.; Smith, J.R.
1979-01-01
In pulsed columns for use in solvent extraction processes, e.g. the reprocessing of nuclear fuel, the horizontal perforated plates inside the column are separated by interplate spacers manufactured from metallic neutron absorbing material. The spacer may be in the form of a spiral or concentric circles separated by radial limbs, or may be of egg-box construction. Suitable neutron absorbing materials include stainless steel containing boron or gadolinium, hafnium metal or alloys of hafnium. (UK)
Directory of Open Access Journals (Sweden)
Chacón, R.
2012-09-01
Full Text Available In this paper, an in-depth analysis of the structural response of concrete-filled tubular structures (CFT is presented. The main objective of the study is to assess the resistance of these structural elements when subjected to lateral displacements. These displacements, together with the corresponding axial forces, represent the actions to which the integral bridges piers are subjected to. For the sake of studying this response, a numerical model is used as a simulation tool over an hypothetical matrix of CFT. These numerical studies together with a wide experimental database found in the literature have been useful for drawing conclusions concerning the cross-sectional capacity of the CFT. A design proposal for this cross-sectional capacity which accounts for confinement is given. This proposal has been compared structurally with the present formulation found in EN1994.
Se presenta el análisis estructural de pilas metálicas tubulares rellenas de hormigón (CFT sometidas a flexo-compresión. El objetivo principal es valorar los mecanismos resistentes de las pilas cuando se someten a un desplazamiento en cabeza. Estos desplazamientos, conjuntamente con el esfuerzo axil de compresión, que en este trabajo se aproxima con un porcentaje de la resistencia plástica a compresión de los CFT, representan las acciones a las cuales se ven sometidos los elementos de este estudio. Se utiliza una herramienta numérica sobre una base hipotética de prototipos de pilas. Los resultados numéricos obtenidos así como los resultados experimentales encontrados en la literatura han permitido extraer conclusiones relativas a la capacidad seccional de los CFT. Se proponen expresiones de diseño relativas a la capacidad resistente de los CFT considerando el efecto del confinamiento y se comparan con los resultados que se derivan de la formulación de EN1994.
International Nuclear Information System (INIS)
Lee, Seung Hyun; Song, Ho Seung; Kim, Jeong Hwan; Cong, Truong Van; Kim, Hui Su; Yeon, Yeong Heum; Lee, Yong seok; Chai, Jong Seo
2015-01-01
The SKKUCY-9 is a compact cyclotron for radioactive isotopes (RI) production of positron emission tomography (PET). Charged particles such as H-ions are accelerated azimuthally within a high intensity electric field (E-field) generated from a radio frequency (RF) system in cyclotron. A high power RF signal is transmitted from an RF amplifier to an RF resonating cavity. The RF system of the SKKUCY-9 operates in continuous wave (CW) mode. If an ion beam were accelerated in the cyclotron, the vacuum level and permittivity would be changed because of beam loading. It causes an impedance shift of the RF resonating cavity. This impedance mismatch generates reflected power that decreases the RF transmitting power. To prevent this situation, an impedance matching system is necessary. This paper describes the impedance matching system of a 20 kW RF amplifier in an SKKUCY-9 compact cyclotron. The impedance matching circuit was designed using both an input stage and output stage, which are divided between the cathode and anode in a vacuum tube that is used as an amplifying device. The equivalent circuit of the matching system is made of passive elements. The characteristic results of designed circuit were calculated using a Smith chart. In assembling, the inductors were replaced by movable stub-line structures. The dimensions of the stub-line structures were optimized with equations and the measurement results. The experiment was performed to find the result values of matching circuit impedance and RF power amplitude
Assembly for connecting the column ends of two capillary columns
International Nuclear Information System (INIS)
Kolb, B.; Auer, M.; Pospisil, P.
1984-01-01
In gas chromatography, the column ends of two capillary columns are inserted into a straight capillary from both sides forming annular gaps. The capillary is located in a tee out of which the capillary columns are sealingly guided, and to which carrier gas is supplied by means of a flushing flow conduit. A ''straight-forward operation'' having capillary columns connected in series and a ''flush-back operation'' are possible. The dead volume between the capillary columns can be kept small
Ricci solitons, Ricci flow and strongly coupled CFT in the Schwarzschild Unruh or Boulware vacua
International Nuclear Information System (INIS)
Figueras, Pau; Lucietti, James; Wiseman, Toby
2011-01-01
The elliptic Einstein-DeTurck equation may be used to numerically find Einstein metrics on Riemannian manifolds. Static Lorentzian Einstein metrics are considered by analytically continuing to Euclidean time. The Ricci-DeTurck flow is a constructive algorithm to solve this equation, and is simple to implement when the solution is a stable fixed point, the only complication being that Ricci solitons may exist which are not Einstein. Here we extend previous work to consider the Einstein-DeTurck equation for Riemannian manifolds with boundaries, and those that continue to static Lorentzian spacetimes which are asymptotically flat, Kaluza-Klein, locally AdS or have extremal horizons. Using a maximum principle, we prove that Ricci solitons do not exist in these cases and so any solution is Einstein. We also argue that the Ricci-DeTurck flow preserves these classes of manifolds. As an example, we simulate the Ricci-DeTurck flow for a manifold with asymptotics relevant for AdS 5 /CFT 4 . Our maximum principle dictates that there are no soliton solutions, and we give strong numerical evidence that there exists a stable fixed point of the flow which continues to a smooth static Lorentzian Einstein metric. Our asymptotics are such that this describes the classical gravity dual relevant for the CFT on a Schwarzschild background in either the Unruh or Boulware vacua. It determines the leading O(N 2 c ) part of the CFT stress tensor, which interestingly is regular on both the future and past Schwarzschild horizons. (paper)
Fake gaps in AdS{sub 3}/CFT{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Belin, Alexandre [Department of Physics, Stanford University,Stanford, CA 94305-4060 (United States); Castro, Alejandra [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, Postbus 94485, 1090 GL Amsterdam (Netherlands); Hung, Ling-Yan [Department of Physics and Center for Field Theory and Particle Physics, Fudan University,220 Handan Road, 200433 Shanghai (China); Collaborative Innovation Center of Advanced Microstructures, Fudan University,220 Handan Road, 200433 Shanghai (China)
2015-11-23
We discuss properties of interpolating geometries in three dimensional gravity in the presence of a chiral anomaly. This anomaly, which introduces an unbalance between left and right central charges, is protected under RG flows. For this simple reason it is impossible to gap a system with such an anomaly. Our goal is to discuss how holography captures this basic and robust feature. We demonstrate the absence of a mass gap by analysing the linearized spectrum and holographic entanglement entropy of these backgrounds in the context of AdS{sub 3}/CFT{sub 2}.
Bariones y gravitones gigantes en el marco de la correspondencia AdS/CFT
Picos Sol, Marco Antonio
2012-01-01
Se construyen y analizan dos tipos de configuraciones que pueden construirse en el espacio dual a la teoría ABJM (en la dualidad AdS_4/CFT_3): gravitones gigantes y vértices bariónicos. Ambas configuraciones hacen uso de la posibilidad de enrrollar branas en ciclos topológicamente no triviales en el lado gravitatorio de la dualidad. Los vértices bariónicos están formados por branas enrrolladas atadas a cuerdas que se extienden hasta la frontera de AdS, y son vistos desde el lado gauge com...
Cusp anomalous dimension and rotating open strings in AdS/CFT
Espíndola, R.; García, J. Antonio
2018-03-01
In the context of AdS/CFT we provide analytical support for the proposed duality between a Wilson loop with a cusp, the cusp anomalous dimension, and the meson model constructed from a rotating open string with high angular momentum. This duality was previously studied using numerical tools in [1]. Our result implies that the minimum of the profile function of the minimal area surface dual to the Wilson loop, is related to the inverse of the bulk penetration of the dual string that hangs from the quark-anti-quark pair (meson) in the gauge theory.
Solvable spectral problems from 2d CFT and \\mathscr{N} = 2 gauge theories
Piątek, M. R.; Pietrykowski, A. R.
2018-02-01
The so-called 2d/4d correspondences connect two-dimensional conformal field theory (2d CFT), \\mathscr{N} = 2 supersymmetric gauge theories and quantum integrable systems. The latter in the simplest case of the SU(2) gauge group are nothing but the quantum-mechanical systems. In the present article we summarize our recent results and list open problems concerning an application of the aforementioned dualities in the studies of spectral problems for some Schrödinger operators with Mathieu-type periodic, periodic PT-symmetric and (Heun’s) elliptic potentials.
AdS5/CFT4 four-point functions of chiral primary operators: Cubic vertices
International Nuclear Information System (INIS)
Lee, Sangmin
1999-01-01
We study the exchange diagrams in the computation of four-point functions of all chiral primary operators in D=4, N=4 super Yang-Mills using AdS/CFT correspondence. We identify all supergravity fields that can be exchanged and compute the cubic couplings. As a byproduct, we also rederive the normalization of the quadratic action of the exchanged fields. The cubic couplings computed in this paper and the propagators studied extensively in the literature can be used to compute almost all the exchange diagrams explicitly. Some issues in computing the complete four-point function in the 'massless sector' are discussed
Causal hydrodynamics of gauge theory plasmas from AdS/CFT duality
International Nuclear Information System (INIS)
Natsuume, Makoto; Okamura, Takashi
2008-01-01
We study causal hydrodynamics (Israel-Stewart theory) of gauge theory plasmas from the AdS/CFT duality. Causal hydrodynamics requires new transport coefficients (relaxation times) and we compute them for a number of supersymmetric gauge theories including the N=4 super Yang-Mills theory. However, the relaxation times obtained from the 'shear mode' do not agree with the ones from the 'sound mode', which implies that the Israel-Stewart theory is not a sufficient framework to describe the gauge theory plasmas.
Integrability for the full spectrum of planar AdS/CFT
International Nuclear Information System (INIS)
Gromov, Nikolay; Kazakov, Vladimir; Vieira, Pedro; Porto Univ.
2009-03-01
We present a set of functional equations defining the anomalous dimensions of arbitrary local single trace operators in planar N=4 SYM theory. It takes the form of a Y-system based on the integrability of the dual superstring σ-model on the AdS 5 x S 5 background. This Y-system passes some very important tests: it incorporates the full asymptotic Bethe ansatz at large length of operator L, including the dressing factor, and it confirms all recently found wrapping corrections. The recently proposed AdS 4 /CFT 3 duality is also treated in a similar fashion. (orig.)
Leenhouts, Robin
2010-01-01
This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…
DEFF Research Database (Denmark)
Aarup, Bendt; Jensen, Lars Rom; Ellegaard, Peter
2005-01-01
CRC is a high-performance steel fibre reinforced concrete with a typical compressive strength of 150 MPa. Design methods for a number of structural elements have been developed since CRC was invented in 1986, but the current project set out to further investigate the range of columns for which...
Nitsche, M
2017-01-01
This book highlights the aspects that need to be considered when designing distillation columns in practice. It discusses the influencing parameters as well as the equations governing them, and presents several numerical examples. The book is intended both for experienced designers and for those who are new to the subject.
Directory of Open Access Journals (Sweden)
Maritza Uribe Vallejo
2009-01-01
Full Text Available Using prequalified connections during the structural design stage becomes increasingly necessary when developing structural en-gineering projects which include steel elements; this is so that the steel elements’ appropriate behavior can be ensured according to the structural system and seismic demand. Unfortunately, the international entities providing this type of information (i.e. FEMA only have a limit series of prequalified connections and such series do not include rigid connections between steel beams and concrete filled tubular (CFT columns having an extended end plate, which has become a very widespread building practice in Colombia. This paper describes the most important aspects of a study at the Universidad Nacional de Colombia concerning the behavior of a steel beam rigidly connected to a CFT-column, using six physical models having different width-thickness ratio (b/t columns. ANSYS v.10 software was used for studying theoretical models (finite elements analysis for comparative analysis of cyclic test theoretical and experimental results for each specimen presented for the qualification phase. The six tested specimens’ hysteretic curves are presented. Several conclusions are drawn concerning finite element validation for this type of connection and the influence of width-thickness ratio (b/t variation and design recommendations for suitable behavior under dynamic loads when this type of connection was used.
Exact correlators on the Wilson loop in N=4 SYM: localization, defect CFT, and integrability
Giombi, Simone; Komatsu, Shota
2018-05-01
We compute a set of correlation functions of operator insertions on the 1 /8 BPS Wilson loop in N=4 SYM by employing supersymmetric localization, OPE and the Gram-Schmidt orthogonalization. These correlators exhibit a simple determinant structure, are position-independent and form a topological subsector, but depend nontrivially on the 't Hooft coupling and the rank of the gauge group. When applied to the 1 /2 BPS circular (or straight) Wilson loop, our results provide an infinite family of exact defect CFT data, including the structure constants of protected defect primaries of arbitrary length inserted on the loop. At strong coupling, we show precise agreement with a direct calculation using perturbation theory around the AdS2 string worldsheet. We also explain the connection of our results to the "generalized Bremsstrahlung functions" previously computed from integrability techniques, reproducing the known results in the planar limit as well as obtaining their finite N generalization. Furthermore, we show that the correlators at large N can be recast as simple integrals of products of polynomials (known as Q-functions) that appear in the Quantum Spectral Curve approach. This suggests an interesting interplay between localization, defect CFT and integrability.
Countermeasures and Functional Testing in Head-Down Tilt Bed Rest (CFT 70)
Cromwell, Ronita L.
2013-01-01
This 70-day bed rest campaign was comprised of 6 integrated studies and conducted at the NASA Flight Analogs Research Unit (FARU). The FARU is located at the University of Texas Medical Branch, Galveston, Texas and is a satellite unit of the Institute for Translational Sciences - Clinical Research Center. This presentation will describe the FARU, discuss the utility of the bed rest platform for use in these studies, and introduce the studies that participated in the CFT 70 bed rest campaign. Information in this presentation will serve as the background for subsequent talks from each individual study. Individual study presentations will discuss preliminary results from completed subjects. Studies included in CFT70 were: ? Physiological Factors Contributing to Post Flight Changes in Functional Performance. J. Bloomberg, NASA ? Integrated Resistance and Aerobic Training Study. L. Ploutz-Snyder, USRA ? Testosterone Supplementation as a Countermeasure Against Musculoskeletal losses during Space Exploration. R. Urban, University of Texas Medical Branch ? Effects of Retronasal Smelling, Variety and Choice on Appetite & Satiety. J. Hunter, Cornell University ? AD ASTRA: Automated Detection of Attitudes and States through Transaction Recordings Analysis. C. Miller, Smart Information Flow Technologies, LLC ? Bed Rest as a Spaceflight Analog to Study Neuro-cognitive Changes: Extent, Longevity, and Neural Bases. R. Seidler, University of Michigan
Protected string spectrum in AdS{sub 3}/CFT{sub 2} from worldsheet integrability
Energy Technology Data Exchange (ETDEWEB)
Baggio, Marco [Instituut voor Theoretische Fysica, KU Leuven,Celestijnenlaan 200D, B-3001 Leuven (Belgium); Sax, Olof Ohlsson [Nordita, Stockholm University and KTH Royal Institute of Technology,Roslagstullsbacken 23, SE-106 91 Stockholm (Sweden); Sfondrini, Alessandro [Institut für Theoretische Physik, ETH Zürich,Wolfgang-Pauli-Str. 27, 8093 Zürich (Switzerland); Stefański, Bogdan Jr. [Centre for Mathematical Science, City, University of London,Northampton Square, EC1V 0HB London (United Kingdom); Torrielli, Alessandro [Department of Mathematics, University of Surrey,Guildford, GU2 7XH (United Kingdom)
2017-04-14
We derive the protected closed-string spectra of AdS{sub 3}/CFT{sub 2} dual pairs with 16 supercharges at arbitrary values of the string tension and of the three-form fluxes. These follow immediately from the all-loop Bethe equations for the spectra of the integrable worldsheet theories. Further, representing the underlying integrable systems as spin chains, we find that their dynamics involves length-changing interactions and that protected states correspond to gapless excitations above the Berenstein-Maldacena-Nastase vacuum. In the case of AdS{sub 3}×S{sup 3}×T{sup 4} the degeneracies of such operators precisely match those of the dual CFT{sub 2} and the supergravity spectrum. On the other hand, we find that for AdS{sub 3}×S{sup 3}×S{sup 3}×S{sup 1} there are fewer protected states than previous supergravity calculations had suggested. In particular, protected states have the same su(2) charge with respect to the two three-spheres.
The lightcone bootstrap and the spectrum of the 3d Ising CFT
Energy Technology Data Exchange (ETDEWEB)
Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study, Princeton, New Jersey 08540 (United States); Walter Burke Institute for Theoretical Physics, Caltech, Pasadena, California 91125 (United States)
2017-03-15
We compute numerically the dimensions and OPE coefficients of several operators in the 3d Ising CFT, and then try to reverse-engineer the solution to crossing symmetry analytically. Our key tool is a set of new techniques for computing infinite sums of SL(2,ℝ) conformal blocks. Using these techniques, we solve the lightcone bootstrap to all orders in an asymptotic expansion in large spin, and suggest a strategy for going beyond the large spin limit. We carry out the first steps of this strategy for the 3d Ising CFT, deriving analytic approximations for the dimensions and OPE coefficients of several infinite families of operators in terms of the initial data {Δ_σ,Δ_ϵ,f_σ_σ_ϵ,f_ϵ_ϵ_ϵ,c_T}. The analytic results agree with numerics to high precision for about 100 low-twist operators (correctly accounting for O(1) mixing effects between large-spin families). Plugging these results back into the crossing equations, we obtain approximate analytic constraints on the initial data.
DEFF Research Database (Denmark)
Trempe Jr., Robert B.; Buthke, Jan
2016-01-01
This book records the efforts of a one-week joint workshop between Master students from Studio 2B of Arkitektskolen Aarhus and Master students from the Harbin Institute of Technology in Harbin, China. The workshop employed nine action words to instigate team-based investigation into the effects o...... as formwork for the shaping of wood veneer. The resulting columns ‘wear’ every aspect of this design pipeline process and display the power of process towards an architectural resolution....
NMFS Water Column Sonar Database
National Oceanic and Atmospheric Administration, Department of Commerce — Water column sonar data are an important component of fishery independent surveys, habitat studies and other research. NMFS water column sonar data are archived here.
The complexity of identifying Ryu-Takayanagi surfaces in AdS{sub 3}/CFT{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Bao, N.; Chatwin-Davies, A. [Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States)
2016-11-07
We present a constructive algorithm for the determination of Ryu-Takayanagi surfaces in AdS{sub 3}/CFT{sub 2} which exploits previously noted connections between holographic entanglement entropy and max-flow/min-cut. We then characterize its complexity as a polynomial time algorithm.
On AdS/CFT correspondence beyond SUGRA: plane waves, free CFTs and double-trace deformations
Energy Technology Data Exchange (ETDEWEB)
Diaz Vazquez, D.E.
2007-09-13
This thesis deals with three corners of the AdS/CFT Correspondence that lie one step beyond the classical supergravity (SUGRA) approximation. We first explore the BMN limit of the duality and study, in particular, the behavior of field theoretic propagators in the corresponding Penrose limit. We unravel the semiclassical (WKB-) exactness of the propagators in the resulting plane wave background metric. Then, we address the limit of vanishing coupling of the conformal field theory (CFT) at large N. In the simplified scenario of Higher Spin/O(N) Vector Model duality, the conformal partial wave (CPW) expansion of scalar four-point functions are reorganized to make them suggestive of a bulk interpretation in term of a consistent truncated massless higher spin theory and their corresponding exchange Witten graphs. We also explore the connection to the interacting O(N) Vector Model at its infra-red fixed point, at leading large N. Finally, coming back to the gauge theory, we study the effect of a relevant double-trace deformations of the boundary CFT on the partition function and its dual bulk interpretation. We show how the one-loop computation in the Anti-de Sitter (AdS) space correctly reproduces the partition function and conformal anomaly of the boundary theory. In all, we get a clean test of the duality beyond the classical SUGRA approximation in the AdS bulk and at the corresponding next-to-leading 1/N order of the CFT at the conformal boundary. (orig.)
DEFF Research Database (Denmark)
Davidsen, J. G.; Thorstad, E. B.; Baktoft, H.
2013-01-01
In this study, 34 anadromous brown trout (sea trout) Salmo trutta were equipped with acoustic transmitters in order to examine whether they performed avoidance behaviour in response to a CFT Legumin (rotenone) treatment in the Norwegian River Vefsna. Migratory behaviour of the S. trutta was monit...
On AdS/CFT correspondence beyond SUGRA: plane waves, free CFTs and double-trace deformations
International Nuclear Information System (INIS)
Diaz Vazquez, D.E.
2007-01-01
This thesis deals with three corners of the AdS/CFT Correspondence that lie one step beyond the classical supergravity (SUGRA) approximation. We first explore the BMN limit of the duality and study, in particular, the behavior of field theoretic propagators in the corresponding Penrose limit. We unravel the semiclassical (WKB-) exactness of the propagators in the resulting plane wave background metric. Then, we address the limit of vanishing coupling of the conformal field theory (CFT) at large N. In the simplified scenario of Higher Spin/O(N) Vector Model duality, the conformal partial wave (CPW) expansion of scalar four-point functions are reorganized to make them suggestive of a bulk interpretation in term of a consistent truncated massless higher spin theory and their corresponding exchange Witten graphs. We also explore the connection to the interacting O(N) Vector Model at its infra-red fixed point, at leading large N. Finally, coming back to the gauge theory, we study the effect of a relevant double-trace deformations of the boundary CFT on the partition function and its dual bulk interpretation. We show how the one-loop computation in the Anti-de Sitter (AdS) space correctly reproduces the partition function and conformal anomaly of the boundary theory. In all, we get a clean test of the duality beyond the classical SUGRA approximation in the AdS bulk and at the corresponding next-to-leading 1/N order of the CFT at the conformal boundary. (orig.)
Aspects of AdS, CFT. Black solutions in gauged supergravity and holographic conductivities
International Nuclear Information System (INIS)
Barisch-Dick, Susanne
2013-01-01
We have met some interesting results within the wide subject of the AdS/CFT correspondence. We have seen how to apply AdS/CFT techniques to calculate the frequency dependent conductivity tensor for field theories dual to a black hole in Einstein-Yang-Mills theory with SU(2) gauge group. Further, we have constructed several new black solutions in N=2 U(1) gauged supergravity in four and five dimensions. The larger part of these solutions behave asymptotically like AdS which makes them interesting within the AdS/CFT context. In addition we found extremal black branes with zero entropy density - the Nernst branes. Nonetheless we are left with some yet unsolved problems. It is very interesting to see what causes the negative entropy production rate we found in chapter 4 for the normal state of the field theory. The next task is to see whether we can find an instability on the gravity side looking at the full Einstein-Yang-Mills equations. Also our work on supergravity solutions in four and five dimension exhibits some ''loose ends''. Since all our four-dimensional Nernst solutions were axion-free it would be nice to find one with axions excited. Moreover, it would be interesting to see whether the singular solutions with flowing γ could be cured by taking into account higher derivative corrections or whether there exist non-singular solutions with non-constant γ. In five dimensions we met problems when adding electric charge. At present we could not find a dyonic solution and we had the impression that having electric charges and having magnetic fields seemed to be somehow complementary to each other. We saw these difficulties even at the beginning when we performed the first-order rewriting since the first-order rewriting in chapter 6 leads to flow equations for the scalars X A which only contain magnetic fields and fluxes but no electric charges. The latter only influence the equations of motion for the X A in an indirect way. However it is possible to find
Marín Jiménez, Juan Francisco
2015-01-01
This project aims to solve the problem of vertical transport of charges raised by a company with the standard UNE 58-132-91/6. The purpose of this project is the industrial design of a system of load handling by a bi-columned lifting device, tractioned by flat belts and steel cables from a transport level to a different level in order to connect two different assembly lines situated at different heights. The goal of this project is lifting a 780 Kg load at a 2.400 mm height....
Directory of Open Access Journals (Sweden)
Simson Garfinkel
2011-06-01
Full Text Available Inheritance powder is the name that was given to poisons, especially arsenic, that were commonly used in the 17th and early 18th centuries to hasten the death of the elderly. For most of the 17th century, arsenic was deadly but undetectable, making it nearly impossible to prove that someone had been poisoned. The first arsenic test produced a gasâ€”hardly something that a scientist could show to a judge. Faced with a growing epidemic of poisonings, doctors and chemists spent decades searching for something better.(see PDF for full column
Natale, A; Bucci, G; Capello, K; Barberio, A; Tavella, A; Nardelli, S; Marangon, S; Ceglie, L
2012-07-01
The objective of this study was to evaluate the performance of the complement fixation test (CFT) with respect to ELISA for the serological diagnosis of Q fever and to assess the role of serology as a tool for the identification of the shedder status. During 2009-2010, sera from 9635 bovines and 3872 small ruminants (3057 goats and 815 sheep) were collected and analyzed with CFT and ELISA. In addition, 2256 bovine, 139 caprine and 72 ovine samples (individual and bulk tank milk samples, fetuses, vaginal swabs and placentae) were analyzed with a real-time PCR kit. The relative sensitivity (Se) and specificity (Sp) of CFT with respect to ELISA were Se 26.56% and Sp 99.71% for cattle and Se 9.96% and Sp 99.94% for small ruminants. To evaluate the correlation between serum-positive status and shedder status, the ELISA, CFT and real-time PCR results were compared. Due to the sampling method and the data storage system, the analysis of individual associations between the serological and molecular tests was possible only for some of the bovine samples. From a statistical point of view, no agreement was observed between the serological and molecular results obtained for fetus and vaginal swab samples. Slightly better agreement was observed between the serological and molecular results obtained for the individual milk samples and between the serological (at least one positive in the examined group) and molecular results for the bulk tank milk (BTM) samples. The CFT results exhibited a better correlation with the shedder status than did the ELISA results. Copyright © 2012 Elsevier Ltd. All rights reserved.
Annular pulse column development studies
International Nuclear Information System (INIS)
Benedict, G.E.
1980-01-01
The capacity of critically safe cylindrical pulse columns limits the size of nuclear fuel solvent extraction plants because of the limited cross-sectional area of plutonium, U-235, or U-233 processing columns. Thus, there is a need to increase the cross-sectional area of these columns. This can be accomplished through the use of a column having an annular cross section. The preliminary testing of a pilot-plant-scale annular column has been completed and is reported herein. The column is made from 152.4-mm (6-in.) glass pipe sections with an 89-mm (3.5-in.) o.d. internal tube, giving an annular width of 32-mm (1.25-in.). Louver plates are used to swirl the column contents to prevent channeling of the phases. The data from this testing indicate that this approach can successfully provide larger-cross-section critically safe pulse columns. While the capacity is only 70% of that of a cylindrical column of similar cross section, the efficiency is almost identical to that of a cylindrical column. No evidence was seen of any non-uniform pulsing action from one side of the column to the other
Functional perturbative RG and CFT data in the ε-expansion
Energy Technology Data Exchange (ETDEWEB)
Codello, A. [Southern Denmark Univ., Odense (Denmark). CP3-Origins; INFN-Sezione di Bologna, Bologna (Italy); Safari, M. [INFN-Sezione di Bologna, Bologna (Italy); Bologna Univ. (Italy). Dipt di Fisica e Astronomia; Vacca, G.P. [INFN-Sezione di Bologna, Bologna (Italy); Zanusso, O. [INFN-Sezione di Bologna, Bologna (Italy); Jena Univ. (Germany). Theoretisch-Physikalisches Inst.
2018-01-15
We show how the use of standard perturbative RG in dimensional regularization allows for a renormalization group-based computation of both the spectrum and a family of coefficients of the operator product expansion (OPE) for a given universality class. The task is greatly simplified by a straightforward generalization of perturbation theory to a functional perturbative RG approach. We illustrate our procedure in the ε-expansion by obtaining the next-to-leading corrections for the spectrum and the leading corrections for the OPE coefficients of Ising and Lee-Yang universality classes and then give several results for the whole family of renormalizable multi-critical models φ{sup 2n}. Whenever comparison is possible our RG results explicitly match the ones recently derived in CFT frameworks. (orig.)
Einstein black holes, free scalars, and AdS/CFT correspondence
International Nuclear Information System (INIS)
Louko, Jorma; Wisniewski, Jacek
2004-01-01
We investigate AdS/CFT correspondence for two families of Einstein black holes in d≥4 dimensions, modeling the boundary conformal field theory by a free conformal scalar field and evaluating the boundary two-point function in the bulk geodesic approximation. For the d≥4 counterpart of the nonrotating Banados-Teitelboim-Zanelli hole and for its Z 2 quotient, the boundary state is thermal in the expected sense, and its stress-energy reflects the properties of the bulk geometry and suggests a novel definition for the mass of the hole. For the generalized Schwarzschild-AdS hole with a flat horizon of topology R d-2 , the boundary stress-energy has a thermal form with energy density proportional to the hole Arnowitt-Deser-Misner mass, but stress-energy corrections from compactified horizon dimensions cannot be consistently included at least for d=5
Holographic two-point functions for Janus interfaces in the D1/D5 CFT
Energy Technology Data Exchange (ETDEWEB)
Chiodaroli, Marco [Department of Physics and Astronomy, Uppsala University, SE-75108 Uppsala (Sweden); Estes, John [Department of Physics, Long Island University,1 University Plaza, Brooklyn, NY 11201 (United States); Korovin, Yegor [Max-Planck-Institut für Gravitationsphysik, Albert-Einstein-Institut, Am Mühlenberg 1, 14476 Golm (Germany)
2017-04-26
This paper investigates scalar perturbations in the top-down supersymmetric Janus solutions dual to conformal interfaces in the D1/D5 CFT, finding analytic closed-form solutions. We obtain an explicit representation of the bulk-to-bulk propagator and extract the two-point correlation function of the dual operator with itself, whose form is not fixed by symmetry alone. We give an expression involving the sum of conformal blocks associated with the bulk-defect operator product expansion and briefly discuss finite-temperature extensions. To our knowledge, this is the first computation of a two-point function which is not completely determined by symmetry for a fully-backreacted, top-down holographic defect.
On excited states in real-time AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Botta-Cantcheff, Marcelo; Martínez, Pedro J.; Silva, Guillermo A. [Instituto de Física de La Plata - CONICET & Departamento de Física - UNLP,C.C. 67, 1900 La Plata (Argentina)
2016-02-25
The Skenderis-van Rees prescription, which allows the calculation of time-ordered correlation functions of local operators in CFT’s using holographic methods is studied and applied for excited states. Calculation of correlators and matrix elements of local CFT operators between generic in/out states are carried out in global Lorentzian AdS. We find the precise form of such states, obtain an holographic formula to compute the inner product between them, and using the consistency with other known prescriptions, we argue that the in/out excited states built according to the Skenderis-Van Rees prescription correspond to coherent states in the (large-N) AdS-Hilbert space. This is confirmed by explicit holographic computations. The outcome of this study has remarkable implications on generalizing the Hartle-Hawking construction for wave functionals of excited states in AdS quantum gravity.
Heisenberg saturation of the Froissart bound from AdS-CFT
International Nuclear Information System (INIS)
Kang, Kyungsik; Nastase, Horatiu
2005-01-01
In a previous paper, we have analyzed high energy QCD from AdS-CFT and proved the saturation of the Froissart bound (a purely QCD proof of which is still lacking). In this Letter we describe the calculation in more physical terms and map it to QCD language. We find a remarkable agreement with the 1952 Heisenberg description of the saturation (pre-QCD!) in terms of shockwave collisions of pion field distributions. It provides a direct map between gauge theory physics and the gravitational physics on the IR brane of the Randall-Sundrum model. Saturation occurs through black hole production on the IR brane, which is in QCD production of a nonlinear pion field soliton of a Born-Infeld action in the hadron collision, that decays into free pions
Giant magnons and spiky strings in the Schrödinger/dipole-deformed CFT correspondence
Georgiou, George; Zoakos, Dimitrios
2018-02-01
We construct semi-classical string solutions of the Schrödinger Sch 5 × S 5 spacetime, which is conjectured to be the gravity dual of a non-local dipole-deformed CFT. They are the counterparts of the giant magnon and spiky string solutions of the undeformed AdS 5 × S 5 to which they flow when the deformation parameter is turned off. They live in an S 3 subspace of the five-sphere along the directions of which the B-field has non-zero components, having also extent in the Sch 5 part of the metric. Finally, we speculate on the form of the dual field theory operators.
A SIMPLE DERIVATION OF FINITE-TEMPERATURE CFT CORRELATORS FROM THE BTZ BLACK HOLE
Directory of Open Access Journals (Sweden)
Satoshi Ohya
2014-04-01
Full Text Available We present a simple Lie-algebraic approach to momentum-space two-point functions of two-dimensional conformal field theory at finite temperature dual to the BTZ black hole. Making use of the real-time prescription of AdS/CFT correspondence and ladder equations of the Lie algebra so(2,2 ∼= sl(2,RL⊕sl(2,RR, we show that the finite-temperature two-point functions in momentum space satisfy linear recurrence relations with respect to the left and right momenta. These recurrence relations are exactly solvable and completely determine the momentum-dependence of retarded and advanced two-point functions of finite-temperature conformal field theory.
Pressure and Compressibility of Conformal Field Theories from the AdS/CFT Correspondence
Directory of Open Access Journals (Sweden)
Brian P. Dolan
2016-05-01
Full Text Available The equation of state associated with N = 4 supersymmetric Yang–Mills in four dimensions, for S U ( N in the large N limit, is investigated using the AdS/CFT correspondence. An asymptotically AdS black-hole on the gravity side provides a thermal background for the Yang–Mills theory on the boundary in which the cosmological constant is equivalent to a volume. The thermodynamic variable conjugate to the cosmological constant is a pressure, and the P - V diagram of the quark-gluon plasma is studied. It is known that there is a critical point where the heat capacity diverges, and this is reflected in the isothermal compressibility. Critical exponents are derived and found to be mean field in the large N limit. The same analysis applied to three- and six-dimensional conformal field theories again yields mean field exponents associated with the compressibility at the critical point.
Constructing an explicit AdS/CFT correspondence with Cartan geometry
Directory of Open Access Journals (Sweden)
Jeffrey S. Hazboun
2018-04-01
Full Text Available An explicit AdS/CFT correspondence is shown for the Lie group SO(4,2. The Lie symmetry structures allow for the construction of two physical theories through the tools of Cartan geometry. One is a gravitational theory that has anti-de Sitter symmetry. The other is also a gravitational theory but is conformally symmetric and lives on 8-dimensional biconformal space. These “extra” four dimensions have the degrees of freedom used to construct a Yang–Mills theory. The two theories, based on AdS or conformal symmetry, have a natural correspondence in the context of their Lie algebras alone where neither SUSY, nor holography, is necessary.
Column-to-column packing variation of disposable pre-packed columns for protein chromatography.
Schweiger, Susanne; Hinterberger, Stephan; Jungbauer, Alois
2017-12-08
In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2-20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10-15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml 2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.
Column: File Cabinet Forensics
Directory of Open Access Journals (Sweden)
Simson Garfinkel
2011-12-01
Full Text Available Researchers can spend their time reverse engineering, performing reverse analysis, or making substantive contributions to digital forensics science. Although work in all of these areas is important, it is the scientific breakthroughs that are the most critical for addressing the challenges that we face.Reverse Engineering is the traditional bread-and-butter of digital forensics research. Companies like Microsoft and Apple deliver computational artifacts (operating systems, applications and phones to the commercial market. These artifacts are bought and used by billions. Some have evil intent, and (if society is lucky, the computers end up in the hands of law enforcement. Unfortunately the original vendors rarely provide digital forensics tools that make their systems amenable to analysis by law enforcement. Hence the need for reverse engineering.(see PDF for full column
Compact electron beam focusing column
Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani
2001-12-01
A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.
Aspects of AdS, CFT. Black solutions in gauged supergravity and holographic conductivities
Energy Technology Data Exchange (ETDEWEB)
Barisch-Dick, Susanne
2013-04-26
We have met some interesting results within the wide subject of the AdS/CFT correspondence. We have seen how to apply AdS/CFT techniques to calculate the frequency dependent conductivity tensor for field theories dual to a black hole in Einstein-Yang-Mills theory with SU(2) gauge group. Further, we have constructed several new black solutions in N=2 U(1) gauged supergravity in four and five dimensions. The larger part of these solutions behave asymptotically like AdS which makes them interesting within the AdS/CFT context. In addition we found extremal black branes with zero entropy density - the Nernst branes. Nonetheless we are left with some yet unsolved problems. It is very interesting to see what causes the negative entropy production rate we found in chapter 4 for the normal state of the field theory. The next task is to see whether we can find an instability on the gravity side looking at the full Einstein-Yang-Mills equations. Also our work on supergravity solutions in four and five dimension exhibits some ''loose ends''. Since all our four-dimensional Nernst solutions were axion-free it would be nice to find one with axions excited. Moreover, it would be interesting to see whether the singular solutions with flowing γ could be cured by taking into account higher derivative corrections or whether there exist non-singular solutions with non-constant γ. In five dimensions we met problems when adding electric charge. At present we could not find a dyonic solution and we had the impression that having electric charges and having magnetic fields seemed to be somehow complementary to each other. We saw these difficulties even at the beginning when we performed the first-order rewriting since the first-order rewriting in chapter 6 leads to flow equations for the scalars X{sup A} which only contain magnetic fields and fluxes but no electric charges. The latter only influence the equations of motion for the X{sup A} in an indirect way. However
International Nuclear Information System (INIS)
Nunez, Alvaro; Starinets, Andrei O.
2003-01-01
We use the Lorentzian AdS/CFT prescription to find the poles of the retarded thermal Green's functions of N=4 SU(N) supersymmetric Yang-Mills theory in the limit of large N and large 't Hooft coupling. In the process, we propose a natural definition for quasinormal modes in an asymptotically AdS spacetime, with boundary conditions dictated by the AdS/CFT correspondence. The corresponding frequencies determine the dispersion laws for the quasiparticle excitations in the dual finite-temperature gauge theory. Correlation functions of operators dual to massive scalar, vector and gravitational perturbations in a five-dimensional AdS-Schwarzschild background are considered. We find asymptotic formulas for quasinormal frequencies in the massive scalar and tensor cases, and an exact expression for vector perturbations. In the long-distance, low-frequency limit we recover results of the hydrodynamic approximation to thermal Yang-Mills theory
Núñez, Alvaro; Starinets, Andrei O.
2003-06-01
We use the Lorentzian AdS/CFT prescription to find the poles of the retarded thermal Green’s functions of N=4 SU(N) supersymmetric Yang-Mills theory in the limit of large N and large ’t Hooft coupling. In the process, we propose a natural definition for quasinormal modes in an asymptotically AdS spacetime, with boundary conditions dictated by the AdS/CFT correspondence. The corresponding frequencies determine the dispersion laws for the quasiparticle excitations in the dual finite-temperature gauge theory. Correlation functions of operators dual to massive scalar, vector and gravitational perturbations in a five-dimensional AdS-Schwarzschild background are considered. We find asymptotic formulas for quasinormal frequencies in the massive scalar and tensor cases, and an exact expression for vector perturbations. In the long-distance, low-frequency limit we recover results of the hydrodynamic approximation to thermal Yang-Mills theory.
Dual QED_3 at “N_F=1/2” is an interacting CFT in the infrared
International Nuclear Information System (INIS)
Roscher, Dietrich; Torres, Emilio; Strack, Philipp
2016-01-01
We study the fate of weakly coupled dual QED_3 in the infrared, that is, a single two-component Dirac fermion coupled to an emergent U(1) gauge field, but without Chern-Simons term. This theory has recently been proposed as a dual description of 2D surfaces of certain topological insulators. Using the renormalization group, we find that the interplay of gauge fluctuations with generated interactions in the four-fermi sector stabilizes an interacting conformal field theory (CFT) with finite four-fermi coupling in the infrared. The emergence of this CFT is due to cancellations in the β-function of the four-fermi coupling special to “N_F=1/2”. We also quantify how a possible “strong” Dirac fermion duality between a free Dirac cone and dual QED_3 would constrain the universal constants of the topological current correlator of the latter.
International Nuclear Information System (INIS)
Zhang Yanfen; Wang Xiaoyu; Cao Li; Guo Qiyong; Wang Xiaoming
2011-01-01
Introduction: Alterations of dopamine in striatal presynaptic terminals play an important role in the hypoxic–ischemic (HI) brain injury. Quantification of DAT levels in the presynaptic site using 11 C-N-2-carbomethoxy-3-(4-fluorophenyl)-tropane ( 11 C-CFT) with positron emission tomography (PET) was applied in studies for Parkinson's disease. The current study investigated the changes in striatal DAT following HI brain injury in newborn piglets using 11 C-CFT PET. Methods: Newborn piglets were subjected to occlusion of bilateral common carotid arteries for 30 min and simultaneous peripheral hypoxia. Brain DAT imaging was performed using PET/CT with 11 C-CFT as the probe in each group (including the control group and HI insult groups). Brain tissues were collected for DAT immunohistochemical (IHC) analysis at each time point post the PET/CT procedure. Sham controls had some operation without HI procedure. Results: A few minutes after intravenous injection of 11 C-CFT, radioactive signals for DAT clearly appeared in the cortical area, striatum and cerebellum of newborn piglets of sham control group and HI insult groups. HI brain insult markedly increased striatal DAT at an early period (P 11 C-CFT PET imaging data and IHC DAT staining data were highly correlated (r=0.844, P 11 C-CFT PET/CT imaging data reflected the dynamic changes of DAT in the striatum in vivo.
Compliance with the AM+L4776L/CFT International Standard; Lessons from a Cross-Country Analysis
Concha Verdugo Yepes
2011-01-01
This paper assesses countries' compliance with the Anti-Money Laundering and Combating the Financing of Terrorism (AML/CFT) international standard during the period 2004 to 2011. We find that overall compliance is low; there is an adverse impact on financial transparency created by the cumulative effects of poor implementation of standards on customer identification; and the current measurements of compliance do not take into account an analysis of ML/FT risk, thereby undermining their credib...
Membranes from monopole operators in ABJM theory: Large angular momentum and M-theoretic AdS4/CFT3
International Nuclear Information System (INIS)
Kovacs, Stefano; Sato, Yuki; Shimada, Hidehiko
2014-01-01
We study the duality between M-theory in AdS 4 ×S 7 /ℤ k and the ABJM N=6 Chern–Simons-matter theory with gauge group U(N)×U(N) and level k, taking N large and k of order 1. In this M-theoretic regime the lack of an explicit formulation of M-theory in AdS 4 ×S 7 /ℤ k makes the gravity side difficult, while the CFT is strongly coupled and the planar approximation is not applicable. We focus on states on the gravity side with large angular momentum J≫1 associated with a single plane of rotation in S 7 and identify their dual operators in the CFT. We show that natural approximation schemes arise on both sides thanks to the presence of the small parameter 1/J. On the AdS side, we use the matrix model of M-theory on the maximally supersymmetric pp-wave background with matrices of size J/k. A perturbative treatment of this matrix model provides a good approximation to M-theory in AdS 4 ×S 7 /ℤ k when N 1/3 ≪J≪N 1/2 . On the CFT side, we study the theory on S 2 ×ℝ with magnetic flux J/k. A Born–Oppenheimer-type expansion arises naturally for large J in spite of the theory being strongly coupled. The energy spectra on the two sides agree at leading order. This provides a non-trivial test of the AdS 4 /CFT 3 correspondence including near-BPS observables associated with membrane degrees of freedom, thus verifying the duality beyond the previously studied sectors corresponding to either BPS observables or the type IIA string regime
Perturbative and non-perturbative approaches to string sigma-models in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Vescovi, Edoardo
2016-10-05
This thesis discusses quantum aspects of type II superstring theories in AdS{sub 5} x S{sup 5} and AdS{sub 4} x CP{sup 3} backgrounds relevant for the AdS/CFT correspondence, using perturbative methods at large string tension and lattice field theory techniques inspired by a work of Roiban and McKeown. We review the construction of the supercoset sigma-model for strings in the AdS{sub 5} x S{sup 5} background, whereas the general quantum dynamics of the superstring in AdS{sub 4} x CP{sup 3} is described by a double dimensional reduction of the supermembrane action in AdS{sub 4} x S{sup 7}. We present a manifestly covariant formalism for semiclassical quantization of strings around arbitrary minimal-area surfaces in AdS{sub 5} x S{sup 5}, expressing the fluctuation operators in terms of intrinsic and extrinsic invariants of the background geometry. We exactly solve the spectral problem for a fourth-order generalization of the Lame differential equation with doubly periodic coefficients in a complex variable. This calculates the one-loop energy of the (J{sub 1},J{sub 2})-string in the SU(2) sector in the limit described by a quantum Landau-Lifshitz model and the bosonic contribution to the energy of the (S,J)-string rotating in AdS{sub 5} and S{sup 5}. Similar techniques calculate the 1/4-BPS latitude Wilson loops in N=4 SYM theory at one loop, normalized to the 1/2-BPS circular loop. Our regularization scheme reproduces the next-to-leading order predicted by supersymmetric localization, up to a remainder function that we discuss upon. We also study the AdS{sub 4} x CP{sup 3} string action expanded around the null cusp background and compute the cusp anomaly up to two loops. This agrees with an all-loop conjectured expression of the ABJM interpolating function. We finally discretize the AdS{sub 5} x S{sup 5} superstring theory in the AdS light-cone gauge and perform lattice simulations at finite coupling with a Monte Carlo algorithm. We measure the string action
Revisiting AdS/CFT at a finite radial cut-off
Energy Technology Data Exchange (ETDEWEB)
Mandal, Gautam; Nayak, Pranjal [Department of Theoretical Physics,Tata Institute of Fundamental Research, Mumbai 400005 (India)
2016-12-22
We revisit AdS/CFT at a finite radial cut-off, specifically in the context of double trace perturbations, O{sub n}= O(x)(∂{sup 2}){sup n}O(x), with arbitrary powers n. As well-known, the standard GKPW prescription, applied to a finite radial cut-off, leads to contact terms in correlators. de Haro et al. http://dx.doi.org/10.1007/s002200100381 introduced bulk counterterms to remove these. This prescription, however, yields additional terms in the correlator corresponding to spurious double trace deformations. Further, if we view the GKPW prescription coupled with the prescription in http://dx.doi.org/10.1007/s002200100381, in terms of a boundary wavefunction, we find that it is incompatible with radial Schrödinger evolution (in the spirit of holographic Wilsonian RG). We consider a more general wavefunction satisfying the Schrödinger equation, and find that generically such wavefunctions generate both (a) double trace deformations and (b) contact terms. However, we find that there exist special choices of these wavefunctions, amounting to a new AdS/CFT prescription at a finite cut-off, so that both (a) and (b) are removed and we obtain a pure power law behaviour for the correlator. We compare these special wavefunctions with a specific RG scheme in field theory. We give a geometric interpretation of these wavefunctions; these correspond to some specific smearing of boundary points in the Witten diagrams. We present a comprehensive calculation of exact double-trace beta-functions for all couplings O{sub n} and match with a holographic computation using the method described above. The matching works with a mapping between the field theory and bulk couplings; such a map is highly constrained because the beta-functions are quadratic and exact on both sides. Our discussions include a generalization of the standard double-trace Wilson-Fisher flow to the space of the infinite number of couplings.
Safety barriers and lighting columns.
Schreuder, D.A.
1972-01-01
Problems arising from the sitting of lighting columns on the central reserve are reviewed, and remedial measures such as break-away lighting supports and installation of safety fences on the central reserve on both sides of the lighting columns are examined.
Note on non-vacuum conformal family contributions to Rényi entropy in two-dimensional CFT
Zhang, Jia-ju
2017-06-01
We calculate the contributions of a general non-vacuum conformal family to Rényi entropy in two-dimensional conformal field theory (CFT). The primary operator of the conformal family can be either non-chiral or chiral, and we denote its scaling dimension by Δ. For the case of two short intervals on a complex plane, we expand the Rényi mutual information by the cross ratio x to order x 2Δ+2. For the case of one interval on a torus with low temperature, we expand the Rényi entropy by q=exp(-2πβ/L), with β being the inverse temperature and L being the spatial period, to order q Δ+2. To make the result meaningful, we require that the scaling dimension Δ cannot be too small. For two intervals on a complex plane we need Δ > 1, and for one interval on a torus we need Δ > 2. We work in the small Newton constant limit on the gravity side and so a large central charge limit on the CFT side, and find matches of gravity and CFT results. Supported by ERC Starting Grant 637844-HBQFTNCER
Marsh, B. D.
2002-12-01
Magma chambers are a necessary concept in understanding the chemical and physical evolution of magma. The concept may well be similar to a transfer function in circuit or time series analysis. It does what needs to be done to transform source magma into eruptible magma. In gravity and geodetic interpretations the causative body is (usually of necessity) geometrically simple and of limited vertical extent; it is clearly difficult to `see' through the uppermost manifestation of the concentrated magma. The presence of plutons in the upper crust has reinforced the view that magma chambers are large pots of magma, but as in the physical representation of a transfer function, actual magma chambers are clearly distinct from virtual magma chambers. Two key features to understanding magmatic systems are that they are vertically integrated over large distances (e.g., 30-100 km), and that all local magmatic processes are controlled by solidification fronts. Heat transfer considerations show that any viable volcanic system must be supported by a vertically extensive plumbing system. Field and geophysical studies point to a common theme of an interconnected stack of sill-like structures extending to great depth. This is a magmatic Mush Column. The large-scale (10s of km) structure resembles the vertical structure inferred at large volcanic centers like Hawaii (e.g., Ryan et al.), and the fine scale (10s to 100s of m) structure is exemplified by ophiolites and deeply eroded sill complexes like the Ferrar dolerites of the McMurdo Dry Valleys, Antarctica. The local length scales of the sill reservoirs and interconnecting conduits produce a rich spectrum of crystallization environments with distinct solidification time scales. Extensive horizontal and vertical mushy walls provide conditions conducive to specific processes of differentiation from solidification front instability to sidewall porous flow and wall rock slumping. The size, strength, and time series of eruptive behavior
Topological Symmetry, Spin Liquids and CFT Duals of Polyakov Model with Massless Fermions
Energy Technology Data Exchange (ETDEWEB)
Unsal, Mithat
2008-04-30
We prove the absence of a mass gap and confinement in the Polyakov model with massless complex fermions in any representation of the gauge group. A U(1){sub *} topological shift symmetry protects the masslessness of one dual photon. This symmetry emerges in the IR as a consequence of the Callias index theorem and abelian duality. For matter in the fundamental representation, the infrared limits of this class of theories interpolate between weakly and strongly coupled conformal field theory (CFT) depending on the number of flavors, and provide an infinite class of CFTs in d = 3 dimensions. The long distance physics of the model is same as certain stable spin liquids. Altering the topology of the adjoint Higgs field by turning it into a compact scalar does not change the long distance dynamics in perturbation theory, however, non-perturbative effects lead to a mass gap for the gauge fluctuations. This provides conceptual clarity to many subtle issues about compact QED{sub 3} discussed in the context of quantum magnets, spin liquids and phase fluctuation models in cuprate superconductors. These constructions also provide new insights into zero temperature gauge theory dynamics on R{sup 2,1} and R{sup 2,1} x S{sup 1}. The confined versus deconfined long distance dynamics is characterized by a discrete versus continuous topological symmetry.
Non-equilibrium scalar two point functions in AdS/CFT
International Nuclear Information System (INIS)
Keränen, Ville; Kleinert, Philipp
2015-01-01
In the first part of the paper, we discuss different versions of the AdS/CFT dictionary out of equilibrium. We show that the Skenderis-van Rees prescription and the “extrapolate” dictionary are equivalent at the level of “in-in” two point functions of free scalar fields in arbitrary asymptotically AdS spacetimes. In the second part of the paper, we calculate two point correlation functions in dynamical spacetimes using the “extrapolate” dictionary. These calculations are performed for conformally coupled scalar fields in examples of spacetimes undergoing gravitational collapse, the AdS 2 -Vaidya spacetime and the AdS 3 -Vaidya spacetime, which allow us to address the problem of thermalization following a quench in the boundary field theory. The computation of the correlators is formulated as an initial value problem in the bulk spacetime. Finally, we compare our results for AdS 3 -Vaidya to results in the previous literature obtained using the geodesic approximation and we find qualitative agreement.
Thermality and excited state Rényi entropy in two-dimensional CFT
Energy Technology Data Exchange (ETDEWEB)
Lin, Feng-Li [Department of Physics, National Taiwan Normal University,Taipei 11677, Taiwan (China); Wang, Huajia [Department of Physics, University of Illinois,Urbana-Champaign, IL 61801 (United States); Zhang, Jia-ju [Dipartimento di Fisica, Università degli Studi di Milano-Bicocca,Piazza della Scienza 3, I-20126 Milano (Italy); Theoretical Physics Division, Institute of High Energy Physics, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China); Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences,19B Yuquan Rd, Beijing 100049 (China)
2016-11-21
We evaluate one-interval Rényi entropy and entanglement entropy for the excited states of two-dimensional conformal field theory (CFT) on a cylinder, and examine their differences from the ones for the thermal state. We assume the interval to be short so that we can use operator product expansion (OPE) of twist operators to calculate Rényi entropy in terms of sum of one-point functions of OPE blocks. We find that the entanglement entropy for highly excited state and thermal state behave the same way after appropriate identification of the conformal weight of the state with the temperature. However, there exists no such universal identification for the Rényi entropy in the short-interval expansion. Therefore, the highly excited state does not look thermal when comparing its Rényi entropy to the thermal state one. As the Rényi entropy captures the higher moments of the reduced density matrix but the entanglement entropy only the average, our results imply that the emergence of thermality depends on how refined we look into the entanglement structure of the underlying pure excited state.
Wilson loops in heavy ion collisions and their calculation in AdS/CFT
Liu, H; Wiedemann, Urs Achim; Liu, Hong; Rajagopal, Krishna; Wiedemann, Urs Achim
2007-01-01
Expectation values of Wilson loops define the nonperturbative properties of the hot medium produced in heavy ion collisions that arise in the analysis of both radiative parton energy loss and quarkonium suppression. We use the AdS/CFT correspondence to calculate the expectation values of such Wilson loops in the strongly coupled plasma of N=4 super Yang-Mills (SYM) theory, allowing for the possibility that the plasma may be moving with some collective flow velocity as is the case in heavy ion collisions. We obtain the N=4 SYM values of the jet quenching parameter $\\hat q$, which describes the energy loss of a hard parton in QCD, and of the velocity-dependence of the quark-antiquark screening length for a moving dipole as a function of the angle between its velocity and its orientation. We show that if the quark-gluon plasma is flowing with velocity v_f at an angle theta with respect to the trajectory of a hard parton, the jet quenching parameter $\\hat q$ is modified by a factor gamma_f(1-v_f cos theta), and s...
Aspects of the zero Λ limit in the AdS/CFT correspondence
Caldeira Costa, R. N.
2014-11-01
We examine the correspondence between QFT observables and bulk solutions in the context of AdS/CFT in the limit as the cosmological constant Λ →0 . We focus specifically on the spacetime metric and a nonbackreacting scalar in the bulk, compute the one-point functions of the dual operators, and determine the necessary conditions for the correspondence to admit a well-behaved zero-Λ limit. We discuss holographic renormalization in this limit and find that it requires schemes that partially break diffeomorphism invariance of the bulk theory. In the specific case of three bulk dimensions, we compute the zero-Λ limit of the holographic Weyl anomaly and reproduce the central charge that arises in the central extension of bms3 . We compute holographically the energy and momentum of those QFT states dual to flat cosmological solutions and to the Kerr solution and find an agreement with the bulk theory. We also compute holographically the renormalized two-point function of a scalar operator in the zero-Λ limit and find it to be consistent with that of a conformal operator in two dimensions fewer. Finally, our results can be used in a new definition of asymptotic Ricci flatness at null infinity based on the zero-Λ limit of asymptotically Einstein manifolds.
Leading CFT constraints on multi-critical models in d>2
Energy Technology Data Exchange (ETDEWEB)
Codello, Alessandro [CP-Origins, University of Southern Denmark,Campusvej 55, 5230 Odense M (Denmark); INFN - Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Safari, Mahmoud [INFN - Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Dipartimento di Fisica e Astronomia, Università di Bologna,via Irnerio 46, 40126 Bologna (Italy); Vacca, Gian Paolo [INFN - Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy); Zanusso, Omar [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universität Jena,Max-Wien-Platz 1, 07743 Jena (Germany); INFN - Sezione di Bologna,via Irnerio 46, 40126 Bologna (Italy)
2017-04-21
We consider the family of renormalizable scalar QFTs with self-interacting potentials of highest monomial ϕ{sup m} below their upper critical dimensions d{sub c}=((2m)/(m−2)), and study them using a combination of CFT constraints, Schwinger-Dyson equation and the free theory behavior at the upper critical dimension. For even integers m≥4 these theories coincide with the Landau-Ginzburg description of multi-critical phenomena and interpolate with the unitary minimal models in d=2, while for odd m the theories are non-unitary and start at m=3 with the Lee-Yang universality class. For all the even potentials and for the Lee-Yang universality class, we show how the assumption of conformal invariance is enough to compute the scaling dimensions of the local operators ϕ{sup k} and of some families of structure constants in either the coupling’s or the ϵ-expansion. For all other odd potentials we express some scaling dimensions and structure constants in the coupling’s expansion.
Leading CFT constraints on multi-critical models in d > 2
DEFF Research Database (Denmark)
Codello, Alessandro; Safari, Mahmoud; Vacca, Gian Paolo
2017-01-01
We consider the family of renormalizable scalar QFTs with self-interacting potentials of highest monomial ϕm below their upper critical dimensions dc=2mm−2, and study them using a combination of CFT constraints, Schwinger-Dyson equation and the free theory behavior at the upper critical dimension....... For even integers m ≥ 4 these theories coincide with the Landau-Ginzburg description of multi-critical phenomena and interpolate with the unitary minimal models in d = 2, while for odd m the theories are non-unitary and start at m = 3 with the Lee-Yang universality class. For all the even potentials...... and for the Lee-Yang universality class, we show how the assumption of conformal invariance is enough to compute the scaling dimensions of the local operators ϕk and of some families of structure constants in either the coupling’s or the ϵ-expansion. For all other odd potentials we express some scaling dimensions...
BPS/CFT Correspondence III: Gauge Origami Partition Function and qq-Characters
Nekrasov, Nikita
2018-03-01
We study generalized gauge theories engineered by taking the low energy limit of the Dp branes wrapping {X × {T}^{p-3}}, with X a possibly singular surface in a Calabi-Yau fourfold Z. For toric Z and X the partition function can be computed by localization, making it a statistical mechanical model, called the gauge origami. The random variables are the ensembles of Young diagrams. The building block of the gauge origami is associated with a tetrahedron, whose edges are colored by vector spaces. We show the properly normalized partition function is an entire function of the Coulomb moduli, for generic values of the {Ω} -background parameters. The orbifold version of the theory defines the qq-character operators, with and without the surface defects. The analytic properties are the consequence of a relative compactness of the moduli spaces M({ěc n}, k) of crossed and spiked instantons, demonstrated in "BPS/CFT correspondence II: instantons at crossroads, moduli and compactness theorem".
Boost-invariant early time dynamics from AdS/CFT
International Nuclear Information System (INIS)
Beuf, Guillaume; Peschanski, Robi; Heller, Michal P.; Janik, Romuald A.
2009-01-01
Boost-invariant dynamics of a strongly-coupled conformal plasma is studied in the regime of early proper-time using the AdS/CFT correspondence. It is shown, in contrast with the late-time expansion, that a scaling solution does not exist. The boundary dynamics in this regime depends on initial conditions encoded in the bulk behavior of a Fefferman-Graham metric coefficient at initial proper-time. The relation between the early-time expansion of the energy density and initial conditions in the bulk of AdS is provided. As a general result it is proven that a singularity of some metric coefficient in Fefferman-Graham frame exists at all times. Requiring that this singularity at τ = 0 is a mere coordinate singularity without the curvature blow-up gives constraints on the possible boundary dynamics. Using a simple Pade resummation for solutions satisfying the regularity constraint, the features of a transition to local equilibrium, and thus to the hydrodynamical late-time regime, have been observed. The impact of this study on the problem of thermalization is discussed.
One-point functions in AdS/dCFT from matrix product states
International Nuclear Information System (INIS)
Buhl-Mortensen, Isak; Leeuw, Marius de; Kristjansen, Charlotte; Zarembo, Konstantin
2016-01-01
One-point functions of certain non-protected scalar operators in the defect CFT dual to the D3-D5 probe brane system with k units of world volume flux can be expressed as overlaps between Bethe eigenstates of the Heisenberg spin chain and a matrix product state. We present a closed expression of determinant form for these one-point functions, valid for any value of k. The determinant formula factorizes into the k=2 result times a k-dependent pre-factor. Making use of the transfer matrix of the Heisenberg spin chain we recursively relate the matrix product state for higher even and odd k to the matrix product state for k=2 and k=3 respectively. We furthermore find evidence that the matrix product states for k=2 and k=3 are related via a ratio of Baxter’s Q-operators. The general k formula has an interesting thermodynamical limit involving a non-trivial scaling of k, which indicates that the match between string and field theory one-point functions found for chiral primaries might be tested for non-protected operators as well. We revisit the string computation for chiral primaries and discuss how it can be extended to non-protected operators.
Boundary conditions and dualities: vector fields in AdS/CFT
International Nuclear Information System (INIS)
Marolf, Donald; Ross, Simo F.
2006-01-01
In AdS, scalar fields with masses slightly above the Breitenlohner-Freedman bound admit a variety of possible boundary conditions which are reflected in the Lagrangian of the dual field theory. Generic small changes in the AdS boundary conditions correspond to deformations of the dual field theory by multi-trace operators. Here we extend this discussion to the case of vector gauge fields in the bulk spacetime using the results of Ishibashi and Wald [hep-th/0402184]. As in the context of scalar fields, general boundary conditions for vector fields involve multi-trace deformations which lead to renormalization-group flows. Such flows originate in ultra-violet CFTs which give new gauge/gravity dualities. At least for AdS 4 /CFT 3 , the dual of the bulk photon appears to be a propagating gauge field instead of the usual R-charge current. Applying similar reasoning to tensor fields suggests the existence of a duality between string theory on AdS 4 and a quantum gravity theory in three dimensions
On information loss in AdS{sub 3}/CFT{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Fitzpatrick, A. Liam [Department of Physics, Boston University,Commonwealth Avenue, Boston, MA 02215 (United States); Kaplan, Jared; Li, Daliang; Wang, Junpu [Department of Physics and Astronomy, Johns Hopkins University, Charles Street, Baltimore, MD 21218 (United States)
2016-05-18
We discuss information loss from black hole physics in AdS{sub 3}, focusing on two sharp signatures infecting CFT{sub 2} correlators at large central charge c: ‘forbidden singularities’ arising from Euclidean-time periodicity due to the effective Hawking temperature, and late-time exponential decay in the Lorentzian region. We study an infinite class of examples where forbidden singularities can be resolved by non-perturbative effects at finite c, and we show that the resolution has certain universal features that also apply in the general case. Analytically continuing to the Lorentzian regime, we find that the non-perturbative effects that resolve forbidden singularities qualitatively change the behavior of correlators at times t∼S{sub BH}, the black hole entropy. This may resolve the exponential decay of correlators at late times in black hole backgrounds. By Borel resumming the 1/c expansion of exact examples, we explicitly identify ‘information-restoring’ effects from heavy states that should correspond to classical solutions in AdS{sub 3}. Our results suggest a line of inquiry towards a more precise formulation of the gravitational path integral in AdS{sub 3}.
T\\overline{T} -deformations, AdS/CFT and correlation functions
Giribet, Gaston
2018-02-01
A solvable irrelevant deformation of AdS3/CFT2 correspondence leading to a theory with Hagedorn spectrum at high energy has been recently proposed. It consists of a single trace deformation of the boundary theory, which is inspired by the recent work on solvable T\\overline{T} deformations of two-dimensional CFTs. Thought of as a worldsheet σ-model, the interpretation of the deformed theory from the bulk viewpoint is that of string theory on a background that interpolates between AdS3 in the IR and a linear dilaton vacuum of little string theory in the UV. The insertion of the operator that realizes the deformation in the correlation functions produces a logarithmic divergence, leading to the renormalization of the primary operators, which thus acquire an anomalous dimension. We compute this anomalous dimension explicitly, and this provides us with a direct way of determining the spectrum of the theory. We discuss this and other features of the correlation functions in presence of the deformation.
Thermodynamic properties of Kehagias-Sfetsos black hole and KS/CFT correspondence
Pradhan, Parthapratim
2017-11-01
We speculate on various thermodynamic features of the inner horizon ({\\mathcal H}-) and outer horizons ({\\mathcal H}+) of Kehagias-Sfetsos (KS) black hole (BH) in the background of the Hořava-Lifshitz gravity. We compute particularly the area product, area sum, area minus and area division of the BH horizons. We find that they all are not showing universal behavior whereas the product is a universal quantity (PRADHAN P., Phys. Lett. B, 747 (2015) 64). Based on these relations, we derive the area bound of all horizons. From the area bound we derive the entropy bound and irreducible mass bound for all the horizons ({\\mathcal H}+/-) . We also observe that the first law of BH thermodynamics and Smarr-Gibbs-Duhem relations do not hold for this BH. The underlying reason behind this failure is due to the scale invariance of the coupling constant. Moreover, we compute the Cosmic-Censorship-Inequality for this BH which gives the lower bound for the total mass of the spacetime and it is supported by the cosmic cencorship conjecture. Finally, we discuss the KS/CFT correspondence via a thermodynamic procedure.
Non-equilibrium scalar two point functions in AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Keränen, Ville [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom); Kleinert, Philipp [Rudolf Peierls Centre for Theoretical Physics, University of Oxford,1 Keble Road, Oxford OX1 3NP (United Kingdom); Merton College, University of Oxford,Merton Street, Oxford OX1 4JD (United Kingdom)
2015-04-22
In the first part of the paper, we discuss different versions of the AdS/CFT dictionary out of equilibrium. We show that the Skenderis-van Rees prescription and the “extrapolate” dictionary are equivalent at the level of “in-in” two point functions of free scalar fields in arbitrary asymptotically AdS spacetimes. In the second part of the paper, we calculate two point correlation functions in dynamical spacetimes using the “extrapolate” dictionary. These calculations are performed for conformally coupled scalar fields in examples of spacetimes undergoing gravitational collapse, the AdS{sub 2}-Vaidya spacetime and the AdS{sub 3}-Vaidya spacetime, which allow us to address the problem of thermalization following a quench in the boundary field theory. The computation of the correlators is formulated as an initial value problem in the bulk spacetime. Finally, we compare our results for AdS{sub 3}-Vaidya to results in the previous literature obtained using the geodesic approximation and we find qualitative agreement.
ADHM and D-instantons in orbifold AdS/CFT duality
International Nuclear Information System (INIS)
Hollowood, Timothy J.; Khoze, Valentin V.
2000-01-01
We consider ADHM instantons in product group gauge theories that arise from D3-branes located at points in the orbifold R 6 /Z p . At finite N we argue that the ADHM construction and collective coordinate integration measure can be deduced from the dynamics of D-instantons in the D3-brane background. For the large-N conformal field theories of this type, we compute a saddle-point approximation of the ADHM integration measure and show that it is proportional to the partition function of D-instantons in the dual AdS 5 xS 5 /Z p background, in agreement with the orbifold AdS/CFT correspondence. Matching the expected behaviour of D-instantons, we find that when S 5 /Z p is smooth a saddle-point solution only exists in the sector where the instanton charges in each gauge group factor are the same. However, when S 5 /Z p is singular, the instanton charges at large N need not be the same and the space of saddle-point solutions has a number of distinct branches which represent the possible fractionations of D-instantons at the singularity. For the theories with a type 0B dual the saddle-point solutions manifest two types of D-instantons
Zooming in on AdS3/CFT2 near a BPS bound
Hartong, Jelle; Lei, Yang; Obers, Niels; Oling, Gerben
2018-05-01
Any ( d + 1)-dimensional CFT with a U(1) flavor symmetry, a BPS bound and an exactly marginal coupling admits a decoupling limit in which one zooms in on the spectrum close to the bound. This limit is an Inönü-Wigner contraction of so(2 , d+1)⊕ u(1) that leads to a relativistic algebra with a scaling generator but no conformal generators. In 2D CFTs, Lorentz boosts are abelian and by adding a second u(1) we find a contraction of two copies of sl(2, ℝ) ⊕ u(1) to two copies of P 2 c , the 2-dimensional centrally extended Poincaré algebra. We show that the bulk is described by a novel non-Lorentzian geometry that we refer to as pseudo-Newton-Cartan geometry. Both the Chern-Simons action on sl(2, ℝ) ⊕ u(1) and the entire phase space of asymptotically AdS3 spacetimes are well-behaved in the corresponding limit if we fix the radial component for the u(1) connection. With this choice, the resulting Newton-Cartan foliation structure is now associated not with time, but with the emerging holographic direction. Since the leaves of this foliation do not mix, the emergence of the holographic direction is much simpler than in AdS3 holography. Furthermore, we show that the asymptotic symmetry algebra of the limit theory consists of a left- and a right-moving warped Virasoro algebra.
Mixed-symmetry fields in AdS(5), conformal fields, and AdS/CFT
Energy Technology Data Exchange (ETDEWEB)
Metsaev, R.R. [Department of Theoretical Physics, P.N. Lebedev Physical Institute,Leninsky prospect 53, Moscow 119991 (Russian Federation)
2015-01-15
Mixed-symmetry arbitrary spin massive, massless, and self-dual massive fields in AdS(5) are studied. Light-cone gauge actions for such fields leading to decoupled equations of motion are constructed. Light-cone gauge formulation of mixed-symmetry anomalous conformal currents and shadows in 4d flat space is also developed. AdS/CFT correspondence for normalizable and non-normalizable modes of mixed-symmetry AdS fields and the respective boundary mixed-symmetry anomalous conformal currents and shadows is studied. We demonstrate that the light-cone gauge action for massive mixed-symmetry AdS field evaluated on solution of the Dirichlet problem amounts to the light-cone gauge 2-point vertex of mixed-symmetry anomalous shadow. Also we show that UV divergence of the action for mixed-symmetry massive AdS field with some particular value of mass parameter evaluated on the Dirichlet problem amounts to the action of long mixed-symmetry conformal field, while UV divergence of the action for mixed-symmetry massless AdS field evaluated on the Dirichlet problem amounts to the action of short mixed-symmetry conformal field. We speculate on string theory interpretation of a model which involves short low-spin conformal fields and long higher-spin conformal fields.
Non-supersymmetric Wilson loop in N = 4 SYM and defect 1d CFT
Beccaria, Matteo; Giombi, Simone; Tseytlin, Arkady A.
2018-03-01
Following Polchinski and Sully (arXiv:1104.5077), we consider a generalized Wilson loop operator containing a constant parameter ζ in front of the scalar coupling term, so that ζ = 0 corresponds to the standard Wilson loop, while ζ = 1 to the locally supersymmetric one. We compute the expectation value of this operator for circular loop as a function of ζ to second order in the planar weak coupling expansion in N = 4 SYM theory. We then explain the relation of the expansion near the two conformal points ζ = 0 and ζ = 1 to the correlators of scalar operators inserted on the loop. We also discuss the AdS5 × S 5 string 1-loop correction to the strong-coupling expansion of the standard circular Wilson loop, as well as its generalization to the case of mixed boundary conditions on the five-sphere coordinates, corresponding to general ζ. From the point of view of the defect CFT1 defined on the Wilson line, the ζ-dependent term can be seen as a perturbation driving a RG flow from the standard Wilson loop in the UV to the supersymmetric Wilson loop in the IR. Both at weak and strong coupling we find that the logarithm of the expectation value of the standard Wilson loop for the circular contour is larger than that of the supersymmetric one, which appears to be in agreement with the 1d analog of the F-theorem.
State Operator Correspondence and Entanglement in AdS2/CFT1
Directory of Open Access Journals (Sweden)
Ashoke Sen
2011-07-01
Full Text Available Since Euclidean global AdS2 space represented as a strip has two boundaries, the state-operator correspondence in the dual CFT1 reduces to the standard map from the operators acting on a single copy of the Hilbert space to states in the tensor product of two copies of the Hilbert space. Using this picture we argue that the corresponding states in the dual string theory living on AdS2 × K are described by the twisted version of the Hartle–Hawking states, the twists being generated by a large unitary group of symmetries that this string theory must possess. This formalism makes natural the dual interpretation of the black hole entropy—as the logarithm of the degeneracy of ground states of the quantum mechanics describing the low energy dynamics of the black hole, and also as an entanglement entropy between the two copies of the same quantum theory living on the two boundaries of global AdS2 separated by the event horizon.
Scalar field theory in the AdS/CFT correspondence revisited
International Nuclear Information System (INIS)
Minces, Pablo; Rivelles, Victor O.
2000-01-01
We consider the role of boundary conditions in the AdS d+1 /CFT d correspondence for the scalar field theory. Also a careful analysis of some limiting cases is presented. We study three possible types of boundary conditions, Dirichlet, Neumann and mixed. We compute the two-point functions of the conformal operators on the boundary for each type of boundary condition. We show how particular choices of the mass require different treatments. In the Dirichlet case we find that there is no double zero in the two-point function of the operator with conformal dimension d/2. The Neumann case leads to new normalizations for the boundary two-point functions. In the massless case we show that the conformal dimension of the boundary conformal operator is precisely the unitarity bound for scalar operators. We find a one-parameter family of boundary conditions in the mixed case. There are again new normalizations for the boundary two-point functions. For a particular choice of the mixed boundary condition and with the mass squared in the range -d 2 /4 2 2 /4+1 the boundary operator has conformal dimension comprised in the interval [(d-2)/2, d/2]. For mass squared m 2 >-d 2 /4+1 the same choice of mixed boundary condition leads to a boundary operator whose conformal dimension is the unitarity bound
Column-Oriented Database Systems (Tutorial)
D. Abadi; P.A. Boncz (Peter); S. Harizopoulos
2009-01-01
textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as
Water Column Sonar Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — The collection and analysis of water column sonar data is a relatively new avenue of research into the marine environment. Primary uses include assessing biological...
LIQUID-LIQUID EXTRACTION COLUMNS
Thornton, J.D.
1957-12-31
This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.
Column-Oriented Database Systems (Tutorial)
Abadi, D.; Boncz, Peter; Harizopoulos, S.
2009-01-01
textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as opposed to traditional database systems that store entire records (rows) one after the other. Reading a subset of a table’s columns becomes faster, at the potential expense of excessive disk-head s...
Quantum field theories coupled to supergravity. AdS/CFT and local couplings
International Nuclear Information System (INIS)
Grosse, J.
2006-01-01
This dissertation is devoted to the investigation of the interplay of supersymmetric Yang-Mills theories (SYM) and supergravity (SUGRA). The topic is studied from two points of view: Firstly from the point of view of AdS/CFT correspondence, which realises the coupling of four dimensional superconformal N=4 SYM theory and ten dimensional type IIB SUGRA in a holographic way. In order to arrive at theories that resemble quantum chromodynamics (QCD) more closely, fundamental fields are introduced using probe D7-branes and nontrivial background configuration are considered. In particular supergravity solutions that are only asymptotically anti-de Sitter and break supersymmetry are used. This allows the description of spontaneous chiral symmetry breaking. The meson spectrum is calculated and the existence of an associated Goldstone mode is demonstrated. Moreover it is shown that highly radially excited mesons are not degenerate. Additionally instanton configurations on the D7-branes are investigated, which lead to a holographic description of the dual field theory's Higgs branch. Finally a holographic description of heavy-light mesons is developed, which are mesons consisting of quarks with a large mass difference, such that a treatment of B mesons can be achieved. The second approach to the topic of this thesis is the technique of socalled space-time dependent couplings (also known as ''local couplings''), where coupling constants are promoted to external sources. This allows to explore the conformal anomaly of quantum field theories coupled to a classical gravity background. The technique is extended to the superfield description of N=1 supergravity, a complete basis for the anomaly is given and the consistency conditions that arise from a cohomological treatment are calculated. Possible implications for an extension of Zamolodchikov's c-theorem to four dimensional supersymmetric quantum field theories are discussed. (orig.)
Quantum field theories coupled to supergravity. AdS/CFT and local couplings
Energy Technology Data Exchange (ETDEWEB)
Grosse, J.
2006-08-03
This dissertation is devoted to the investigation of the interplay of supersymmetric Yang-Mills theories (SYM) and supergravity (SUGRA). The topic is studied from two points of view: Firstly from the point of view of AdS/CFT correspondence, which realises the coupling of four dimensional superconformal N=4 SYM theory and ten dimensional type IIB SUGRA in a holographic way. In order to arrive at theories that resemble quantum chromodynamics (QCD) more closely, fundamental fields are introduced using probe D7-branes and nontrivial background configuration are considered. In particular supergravity solutions that are only asymptotically anti-de Sitter and break supersymmetry are used. This allows the description of spontaneous chiral symmetry breaking. The meson spectrum is calculated and the existence of an associated Goldstone mode is demonstrated. Moreover it is shown that highly radially excited mesons are not degenerate. Additionally instanton configurations on the D7-branes are investigated, which lead to a holographic description of the dual field theory's Higgs branch. Finally a holographic description of heavy-light mesons is developed, which are mesons consisting of quarks with a large mass difference, such that a treatment of B mesons can be achieved. The second approach to the topic of this thesis is the technique of socalled space-time dependent couplings (also known as ''local couplings''), where coupling constants are promoted to external sources. This allows to explore the conformal anomaly of quantum field theories coupled to a classical gravity background. The technique is extended to the superfield description of N=1 supergravity, a complete basis for the anomaly is given and the consistency conditions that arise from a cohomological treatment are calculated. Possible implications for an extension of Zamolodchikov's c-theorem to four dimensional supersymmetric quantum field theories are discussed. (orig.)
Radiotracer Imaging of Sediment Columns
Moses, W. W.; O'Neil, J. P.; Boutchko, R.; Nico, P. S.; Druhan, J. L.; Vandehey, N. T.
2010-12-01
Nuclear medical PET and SPECT cameras routinely image radioactivity concentration of gamma ray emitting isotopes (PET - 511 keV; SPECT - 75-300 keV). We have used nuclear medical imaging technology to study contaminant transport in sediment columns. Specifically, we use Tc-99m (T1/2 = 6 h, Eγ = 140 keV) and a SPECT camera to image the bacteria mediated reduction of pertechnetate, [Tc(VII)O4]- + Fe(II) → Tc(IV)O2 + Fe(III). A 45 mL bolus of Tc-99m (32 mCi) labeled sodium pertechnetate was infused into a column (35cm x 10cm Ø) containing uranium-contaminated subsurface sediment from the Rifle, CO site. A flow rate of 1.25 ml/min of artificial groundwater was maintained in the column. Using a GE Millennium VG camera, we imaged the column for 12 hours, acquiring 44 frames. As the microbes in the sediment were inactive, we expected most of the iron to be Fe(III). The images were consistent with this hypothesis, and the Tc-99m pertechnetate acted like a conservative tracer. Virtually no binding of the Tc-99m was observed, and while the bolus of activity propagated fairly uniformly through the column, some inhomogeneity attributed to sediment packing was observed. We expect that after augmentation by acetate, the bacteria will metabolically reduce Fe(III) to Fe(II), leading to significant Tc-99m binding. Imaging sediment columns using nuclear medicine techniques has many attractive features. Trace quantities of the radiolabeled compounds are used (micro- to nano- molar) and the half-lives of many of these tracers are short (Image of Tc-99m distribution in a column containing Rifle sediment at four times.
Performance evaluation of a rectifier column using gamma column scanning
Directory of Open Access Journals (Sweden)
Aquino Denis D.
2017-12-01
Full Text Available Rectifier columns are considered to be a critical component in petroleum refineries and petrochemical processing installations as they are able to affect the overall performance of these facilities. It is deemed necessary to monitor the operational conditions of such vessels to optimize processes and prevent anomalies which could pose undesired consequences on product quality that might lead to huge financial losses. A rectifier column was subjected to gamma scanning using a 10-mCi Co-60 source and a 2-inch-long detector in tandem. Several scans were performed to gather information on the operating conditions of the column under different sets of operating parameters. The scan profiles revealed unexpected decreases in the radiation intensity at vapour levels between trays 2 and 3, and between trays 4 and 5. Flooding also occurred during several scans which could be attributed to parametric settings.
Energy Technology Data Exchange (ETDEWEB)
Schmidt, R.
2007-03-15
The present work is addressed to defects and boundaries in quantum field theory considering the application to AdS/CFT correspondence. We examine interactions of fermions with spins localised on these boundaries. Therefore, an algebra method is emphasised adding reflection and transmission terms to the canonical quantisation prescription. This method has already been applied to bosons in two space-time dimensions before. We show the possibilities of such reflection-transmission algebras in two, three, and four dimensions. We compare with models of solid state physics as well as with the conformal field theory approach to the Kondo effect. Furthermore, we discuss ansatzes of extensions to lattice structures. (orig.)
Jones, Andrew; Pravadali-Cekic, Sercan; Dennis, Gary R; Shalliker, R Andrew
2015-08-19
Post Column derivatisation (PCD) coupled with high performance liquid chromatography or ultra-high performance liquid chromatography is a powerful tool in the modern analytical laboratory, or at least it should be. One drawback with PCD techniques is the extra post-column dead volume due to reaction coils used to enable adequate reaction time and the mixing of reagents which causes peak broadening, hence a loss of separation power. This loss of efficiency is counter-productive to modern HPLC technologies, -such as UHPLC. We reviewed 87 PCD methods published from 2009 to 2014. We restricted our review to methods published between 2009 and 2014, because we were interested in the uptake of PCD methods in UHPLC environments. Our review focused on a range of system parameters including: column dimensions, stationary phase and particle size, as well as the geometry of the reaction loop. The most commonly used column in the methods investigated was not in fact a modern UHPLC version with sub-2-micron, (or even sub-3-micron) particles, but rather, work-house columns, such as, 250 × 4.6 mm i.d. columns packed with 5 μm C18 particles. Reaction loops were varied, even within the same type of analysis, but the majority of methods employed loop systems with volumes greater than 500 μL. A second part of this review illustrated briefly the effect of dead volume on column performance. The experiment evaluated the change in resolution and separation efficiency of some weak to moderately retained solutes on a 250 × 4.6 mm i.d. column packed with 5 μm particles. The data showed that reaction loops beyond 100 μL resulted in a very serious loss of performance. Our study concluded that practitioners of PCD methods largely avoid the use of UHPLC-type column formats, so yes, very much, PCD is incompatible with the modern HPLC column. Copyright © 2015. Published by Elsevier B.V.
NOx retention in scrubbing column
International Nuclear Information System (INIS)
Nakazone, A.K.; Costa, R.E.; Lobao, A.S.T.; Matsuda, H.T.; Araujo, B.F.
1988-07-01
During the UO 2 dissolution in nitric acid, some different species of NO x are released. The off gas can either be refluxed to the dissolver or be released and retained on special columns. The final composition of the solution is the main parameter to take in account. A process for nitrous gases retention using scubber columns containing H 2 O or diluted HNO 3 is presented. Chemiluminescence measurement was employed to NO x evalution before and after scrubbing. Gas flow, temperature, residence time are the main parameters considered in this paper. For the dissolution of 100g UO 2 in 8M nitric acid, a 6NL/h O 2 flow was the best condition for the NO/NO 2 oxidation with maximum adsorption in the scrubber columns. (author) [pt
Column study for the evaluation of the transport properties of polyphenol-coated nanoiron.
Mystrioti, C; Papassiopi, N; Xenidis, A; Dermatas, D; Chrysochoou, M
2015-01-08
Injection of a nano zero valent iron (nZVI) suspension in the subsurface is a remedial option for obtaining the in situ reduction and immobilization of hexavalent chromium in contaminated aquifers. Prerequisite for the successful implementation of this technology is that the nanoparticles form a stable colloidal suspension with good transport properties when delivered in the subsurface. In this study we produced stable suspensions of polyphenol-coated nZVI (GT-nZVI) and we evaluated their transport behavior through representative porous media. Two types of porous materials were tested: (a) silica sand as a typical inert medium and (b) a mixture of calcareous soil and sand. The transport of GT-nZVI through the sand column was effectively described using a classic 1-D convection-dispersion flow equation (CDE) in combination with the colloid filtration theory (CFT). The calculations indicate that nZVI travel distance will be limited in the range 2.5-25cm for low Darcy velocities (0.1-1m/d) and in the order of 2.5m at higher velocities (10m/d). The mobility of GT-nZVI suspension in the soil-sand column is lower and is directly related to the progress of the neutralization reactions between the acidic GT-nZVI suspension and soil calcite. Copyright © 2014 Elsevier B.V. All rights reserved.
Chromatographic properties PLOT multicapillary columns.
Nikolaeva, O A; Patrushev, Y V; Sidelnikov, V N
2017-03-10
Multicapillary columns (MCCs) for gas chromatography make it possible to perform high-speed analysis of the mixtures of gaseous and volatile substances at a relatively large amount of the loaded sample. The study was performed using PLOT MCCs for gas-solid chromatography (GSC) with different stationary phases (SP) based on alumina, silica and poly-(1-trimethylsilyl-1-propyne) (PTMSP) polymer as well as porous polymers divinylbenzene-styrene (DVB-St), divinylbenzene-vinylimidazole (DVB-VIm) and divinylbenzene-ethylene glycol dimethacrylate (DVB-EGD). These MCCs have the efficiency of 4000-10000 theoretical plates per meter (TP/m) and at a column length of 25-30cm can separate within 10-20s multicomponent mixtures of substances belonging to different classes of chemical compounds. The sample amount not overloading the column is 0.03-1μg and depends on the features of a porous layer. Examples of separations on some of the studied columns are considered. Copyright © 2017 Elsevier B.V. All rights reserved.
Modeling of column apparatus processes
Boyadjiev, Christo; Boyadjiev, Boyan; Popova-Krumova, Petya
2016-01-01
This book presents a new approach for the modeling of chemical and interphase mass transfer processes in industrial column apparatuses, using convection-diffusion and average-concentration models. The convection-diffusion type models are used for a qualitative analysis of the processes and to assess the main, small and slight physical effects, and then reject the slight effects. As a result, the process mechanism can be identified. It also introduces average concentration models for quantitative analysis, which use the average values of the velocity and concentration over the cross-sectional area of the column. The new models are used to analyze different processes (simple and complex chemical reactions, absorption, adsorption and catalytic reactions), and make it possible to model the processes of gas purification with sulfur dioxide, which form the basis of several patents.
Studies of column supported towers
International Nuclear Information System (INIS)
Chauvel, D.; Costaz, J.-L.
1991-01-01
As a result of a research and development programme into the civil engineering of cooling towers launched in 1978 by Electricite de France, very high cooling towers were built at Golfech and Chooz, in France, using column supports. This paper discusses the evolution of this new type of support from classical diagonal supports, presents some of the results of design calculations and survey measurements taken during construction of the shell and analyses the behaviour of the structure. (author)
SPEEDUPtrademark ion exchange column model
International Nuclear Information System (INIS)
Hang, T.
2000-01-01
A transient model to describe the process of loading a solute onto the granular fixed bed in an ion exchange (IX) column has been developed using the SpeedUptrademark software package. SpeedUp offers the advantage of smooth integration into other existing SpeedUp flowsheet models. The mathematical algorithm of a porous particle diffusion model was adopted to account for convection, axial dispersion, film mass transfer, and pore diffusion. The method of orthogonal collocation on finite elements was employed to solve the governing transport equations. The model allows the use of a non-linear Langmuir isotherm based on an effective binary ionic exchange process. The SpeedUp column model was tested by comparing to the analytical solutions of three transport problems from the ion exchange literature. In addition, a sample calculation of a train of three crystalline silicotitanate (CST) IX columns in series was made using both the SpeedUp model and Purdue University's VERSE-LC code. All test cases showed excellent agreement between the SpeedUp model results and the test data. The model can be readily used for SuperLigtrademark ion exchange resins, once the experimental data are complete
Two generalizations of column-convex polygons
International Nuclear Information System (INIS)
Feretic, Svjetlan; Guttmann, Anthony J
2009-01-01
Column-convex polygons were first counted by area several decades ago, and the result was found to be a simple, rational, generating function. In this work we generalize that result. Let a p-column polyomino be a polyomino whose columns can have 1, 2, ..., p connected components. Then column-convex polygons are equivalent to 1-convex polyominoes. The area generating function of even the simplest generalization, namely 2-column polyominoes, is unlikely to be solvable. We therefore define two classes of polyominoes which interpolate between column-convex polygons and 2-column polyominoes. We derive the area generating functions of those two classes, using extensions of existing algorithms. The growth constants of both classes are greater than the growth constant of column-convex polyominoes. Rather tight lower bounds on the growth constants complement a comprehensive asymptotic analysis.
Extensive numerical study of a D-brane, anti-D-brane system in AdS5/CFT4
International Nuclear Information System (INIS)
Hegedűs, Árpád
2015-01-01
In this paper the hybrid-NLIE approach of http://dx.doi.org/10.1007/JHEP08(2012)022 is extended to the ground state of a D-brane anti-D-brane system in AdS/CFT. The hybrid-NLIE equations presented in the paper are finite component alternatives of the previously proposed TBA equations and they admit an appropriate framework for the numerical investigation of the ground state of the problem. Straightforward numerical iterative methods fail to converge, thus new numerical methods are worked out to solve the equations. Our numerical data confirm the previous TBA data. In view of the numerical results the mysterious L=1 case is also commented in the paper.
International Nuclear Information System (INIS)
Loran, Farhang
2004-01-01
We solve Klein-Gordon equation for massless scalars on (d+1)-dimensional Minkowski (Euclidean) space in terms of the Cauchy data on the hypersurface t=0. By inserting the solution into the action of massless scalars in Minkowski (Euclidean) space we obtain the action of dual theory on the boundary t=0 which is exactly the holographic dual of conformally coupled scalars on (d+1)-dimensional (Euclidean anti) de Sitter space obtained in (A)dS/CFT correspondence. The observed equivalence of dual theories is explained using the one-to-one map between conformally coupled scalar fields on Minkowski (Euclidean) space and (Euclidean anti) de Sitter space which is an isomorphism between the hypersurface t=0 of Minkowski (Euclidean) space and the boundary of (A)dS space
Non-Abelian T-duality and the AdS/CFT correspondence: New N=1 backgrounds
Energy Technology Data Exchange (ETDEWEB)
Itsios, Georgios, E-mail: gitsios@upatras.gr [Department of Engineering Sciences, University of Patras, 26110 Patras (Greece); Department of Mathematics, University of Surrey, Guildford GU2 7XH (United Kingdom); Núñez, Carlos, E-mail: c.nunez@swansea.ac.uk [Swansea University, School of Physical Sciences, Singleton Park, Swansea SA2 8PP (United Kingdom); Sfetsos, Konstadinos, E-mail: k.sfetsos@surrey.ac.uk [Department of Mathematics, University of Surrey, Guildford GU2 7XH (United Kingdom); Department of Engineering Sciences, University of Patras, 26110 Patras (Greece); Thompson, Daniel C., E-mail: dthompson@tena4.vub.ac.be [Theoretische Natuurkunde, Vrije Universiteit Brussel (Belgium); International Solvay Institutes, Pleinlaan 2, B-1050 Brussels (Belgium)
2013-08-01
We consider non-Abelian T-duality on N=1 supergravity backgrounds possessing well understood field theory duals. For the case of D3-branes at the tip of the conifold, we dualise along an SU(2) isometry. The result is a type-IIA geometry whose lift to M-theory is of the type recently proposed by Bah et al. as the dual to certain N=1 SCFT quivers produced by M5-branes wrapping a Riemann surface. In the non-conformal cases we find smooth duals in massive IIA supergravity with a Romans mass naturally quantised. We initiate the interpretation of these geometries in the context of AdS/CFT correspondence. We show that the central charge and the entanglement entropy are left invariant by this dualisation. The backgrounds suggest a form of Seiberg duality in the dual field theories which also exhibit domain walls and confinement in the infrared.
International Nuclear Information System (INIS)
Hansen, Tobias
2015-07-01
This thesis covers two main topics: the tensorial structure of quantum field theory correlators in general spacetime dimensions and a method for computing string theory scattering amplitudes directly in target space. In the first part tensor structures in generic bosonic CFT correlators and scattering amplitudes are studied. To this end arbitrary irreducible tensor representations of SO(d) (traceless mixed-symmetry tensors) are encoded in group invariant polynomials, by contracting with sets of commuting and anticommuting polarization vectors which implement the index symmetries of the tensors. The tensor structures appearing in CFT d correlators can then be inferred by studying these polynomials in a d + 2 dimensional embedding space. It is shown with an example how these correlators can be used to compute general conformal blocks describing the exchange of mixed-symmetry tensors in four-point functions, which are crucial for advancing the conformal bootstrap program to correlators of operators with spin. Bosonic string theory lends itself as an ideal example for applying the same methods to scattering amplitudes, due to its particle spectrum of arbitrary mixed-symmetry tensors. This allows in principle the definition of on-shell recursion relations for string theory amplitudes. A further chapter introduces a different target space definition of string scattering amplitudes. As in the case of on-shell recursion relations, the amplitudes are expressed in terms of their residues via BCFW shifts. The new idea here is that the residues are determined by use of the monodromy relations for open string theory, avoiding the infinite sums over the spectrum arising in on-shell recursion relations. Several checks of the method are presented, including a derivation of the Koba-Nielsen amplitude in the bosonic string. It is argued that this method provides a target space definition of the complete S-matrix of string theory at tree-level in a at background in terms of a small
Origin of inflation in CFT driven cosmology. R2-gravity and non-minimally coupled inflaton models
International Nuclear Information System (INIS)
Barvinsky, A.O.; Kamenshchik, A.Yu.; Nesterov, D.V.
2015-01-01
We present a detailed derivation of the recently suggested new type of hill-top inflation [arXiv:1509.07270] originating from the microcanonical density matrix initial conditions in cosmology driven by conformal field theory (CFT). The cosmological instantons of topology S 1 x S 3 , which set up these initial conditions, have the shape of a garland with multiple periodic oscillations of the scale factor of the spatial S 3 -section. They describe underbarrier oscillations of the inflaton and scale factor in the vicinity of the inflaton potential maximum, which gives a sufficient amount of inflation required by the known CMB data. We build the approximation of two coupled harmonic oscillators for these garland instantons and show that they can generate inflation consistent with the parameters of the CMB primordial power spectrum in the non-minimal Higgs inflation model and in R 2 gravity. In particular, the instanton solutions provide smallness of inflationary slow-roll parameters ε and η < 0 and their relation ε ∝ η 2 characteristic of these two models. We present the mechanism of formation of hill-like inflaton potentials, which is based on logarithmic loop corrections to the asymptotically shift-invariant tree-level potentials of these models in the Einstein frame. We also discuss the role of R 2 -gravity as an indispensable finite renormalization tool in the CFT driven cosmology, which guarantees the nondynamical (ghost free) nature of its scale factor and special properties of its cosmological garland-type instantons. Finally, as a solution to the problem of hierarchy between the Planckian scale and the inflation scale we discuss the concept of a hidden sector of conformal higher spin fields. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Barvinsky, A. O., E-mail: barvin@td.lpi.ru [Theory Department, Lebedev Physics Institute, Leninsky Prospect 53, 119991, Moscow (Russian Federation); Department of Physics, Tomsk State University, Lenin Ave. 36, 634050, Tomsk (Russian Federation); Department of Physics and Astronomy, Pacific Institute for Theoretical Physics, UBC, 6224 Agricultural Road, V6T1Z1, Vancouver, BC (Canada); Kamenshchik, A. Yu., E-mail: kamenshchik@bo.infn.it [Dipartimento di Fisica e Astronomia, Università di Bologna and INFN, Via Irnerio 46, 40126, Bologna (Italy); L. D. Landau Institute for Theoretical Physics, 119334, Moscow (Russian Federation); Nesterov, D. V., E-mail: nesterov@td.lpi.it [Theory Department, Lebedev Physics Institute, Leninsky Prospect 53, 119991, Moscow (Russian Federation)
2015-12-11
We present a detailed derivation of the recently suggested new type of hill-top inflation originating from the microcanonical density matrix initial conditions in cosmology driven by conformal field theory (CFT). The cosmological instantons of topology S{sup 1}×S{sup 3}, which set up these initial conditions, have the shape of a garland with multiple periodic oscillations of the scale factor of the spatial S{sup 3}-section. They describe underbarrier oscillations of the inflaton and scale factor in the vicinity of the inflaton potential maximum, which gives a sufficient amount of inflation required by the known CMB data. We build the approximation of two coupled harmonic oscillators for these garland instantons and show that they can generate inflation consistent with the parameters of the CMB primordial power spectrum in the non-minimal Higgs inflation model and in R{sup 2} gravity. In particular, the instanton solutions provide smallness of inflationary slow-roll parameters ϵ and η<0 and their relation ϵ∼η{sup 2} characteristic of these two models. We present the mechanism of formation of hill-like inflaton potentials, which is based on logarithmic loop corrections to the asymptotically shift-invariant tree-level potentials of these models in the Einstein frame. We also discuss the role of R{sup 2}-gravity as an indispensable finite renormalization tool in the CFT driven cosmology, which guarantees the non-dynamical (ghost free) nature of its scale factor and special properties of its cosmological garland-type instantons. Finally, as a solution to the problem of hierarchy between the Planckian scale and the inflation scale we discuss the concept of a hidden sector of conformal higher spin fields.
29 CFR 1926.755 - Column anchorage.
2010-07-01
... 29 Labor 8 2010-07-01 2010-07-01 false Column anchorage. 1926.755 Section 1926.755 Labor... (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Steel Erection § 1926.755 Column anchorage. (a) General requirements for erection stability. (1) All columns shall be anchored by a minimum of 4 anchor...
Adsorption columns for use in radioimmunoassays
International Nuclear Information System (INIS)
1976-01-01
Adsorption columns are provided which can be utilized in radioimmunoassay systems such as those involving the separation of antibody-antigen complexes from free antigens. The preparation of the columns includes the treatment of retaining substrate material to render it hydrophilic, preparation and degassing of the separation material and loading the column
Thermal process of an air column
International Nuclear Information System (INIS)
Lee, F.T.
1994-01-01
Thermal process of a hot air column is discussed based on laws of thermodynamics. The kinetic motion of the air mass in the column can be used as a power generator. Alternatively, the column can also function as a exhaust/cooler
Alvarez, Guillermo; Caldwell, Colleen A.; Kruse, Carter G.
2017-01-01
Amphibians may experience collateral effects if exposed to CFT Legumine (5% rotenone), a piscicide that is used to remove invasive fish. A series of 48-h static toxicity tests assessed the acute effects of CFT Legumine on multi-aged tadpoles of the federally listed Chiricahua leopard frog Lithobates chiricahuensis, the widespread northern leopard frog L. pipiens, and the increasingly invasive American bullfrog L. catesbeianus. At the earliest Gosner stages (GS 21–25), Chiricahua leopard frogs were more sensitive to CFT Legumine (median lethal concentration [LC50] = 0.41–0.58 mg/L) than American bullfrogs (LC50 = 0.63–0.69 mg/L) and northern leopard frogs (LC50 = 0.91 and 1.17 mg/L). As tadpoles developed (i.e., increase in GS), their sensitivity to rotenone decreased. In a separate series of 48-h static nonrenewal toxicity tests, tadpoles (GS 21–25 and GS 31–36) of all three species were exposed to piscicidal concentrations of CFT Legumine (0.5, 1.0, and 2.0 mg/L) to assess postexposure effects on metamorphosis. In survivors of all three species at both life stages, the time to tail resorption was nearly doubled in comparison with that of controls. For example, mid-age (GS 31–36) Chiricahua leopard frog tadpoles required 210.7 h to complete tail resorption, whereas controls required 108.5 h. However, because tail resorption is a relatively short period in metamorphosis, the total duration of development (days from posthatch to complete metamorphosis) and the final weight did not differ in either age-group surviving nominal concentrations of 0.5-, 1.0-, and 2.0-mg/L CFT Legumine relative to controls. This research demonstrates that the CFT Legumine concentrations commonly used in field applications to remove unwanted fish could result in considerable mortality of the earliest stages of Lithobates species. In addition to acute lethality, piscicide treatments may result in delayed tail resorption, which places the tadpoles at risk by increasing
Evaluation of Packed Distillation Columns I - Atmospheric Pressure
National Research Council Canada - National Science Library
Reynolds, Thaine
1951-01-01
.... Four column-packing combinations of the glass columns and four column-packing combinations of the steel columns were investigated at atmospheric pressure using a test mixture of methylcyclohexane...
Oscillating water column structural model
Energy Technology Data Exchange (ETDEWEB)
Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-09-01
An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.
Picobubble enhanced column flotation of fine coal
Energy Technology Data Exchange (ETDEWEB)
Tao, D.; Yu, S.; Parekh, B.K. [University of Kentucky, Lexington, KY (United States). Mining Engineering
2006-07-01
The purpose is to study the effectiveness of picobubbles in the column flotation of -28 mesh fine coal particles. A flotation column with a picobubble generator was developed and tested for enhancing the recovery of ultrafine coal particles. The picobubble generator was designed using the hydrodynamic cavitation principle. A metallurgical and a steam coal were tested in the apparatus. The results show that the use of picobubbles in a 2in. flotation column increased the recovery of fine coal by 10 to 30%. The recovery rate varied with feed rate, collector dosage, and other column conditions. 40 refs., 8 figs., 2 tabs.
Thermally stable dexsil-400 glass capillary columns
International Nuclear Information System (INIS)
Maskarinec, M.P.; Olerich, G.
1980-01-01
The factors affecting efficiency, thermal stability, and reproducibility of Dexsil-400 glass capillary columns for gas chromatography in general, and for polycyclic aromatic hydrocarbons (PAHs) in particular were investigated. Columns were drawn from Kimble KG-6 (soda-lime) glass or Kimox (borosilicate) glass. All silylation was carried out at 200 0 C. Columns were coated according to the static method. Freshly prepared, degassed solutions of Dexsil-400 in pentane or methylene chloride were used. Thermal stability of the Dexsil 400 columns with respect to gas chromatography/mass spectrometry (GC/MS) were tested. Column-to-column variability is a function of each step in the fabrication of the columns. The degree of etching, extent of silylation, and stationary phase film thickness must be carefully controlled. The variability in two Dexsil-400 capillary column prepared by etching, silylation with solution of hexa methyl disilazone (HMDS), and static coating is shown and also indicates the excellent selectivity of Dexsil-400 for the separation of alkylated aromatic compounds. The wide temperature range of Dexsil-400 and the high efficiency of the capillary columns also allow the analysis of complex mixtures with minimal prefractionation. Direct injection of a coal liquefaction product is given. Analysis by GC/MS indicated the presence of parent PAHs, alkylated PAHs, nitrogen and sulfur heterocycles, and their alkylated derivatives. 4 figures
Laser surface wakefield in a plasma column
International Nuclear Information System (INIS)
Gorbunov, L.M.; Mora, P.; Ramazashvili, R.R.
2003-01-01
The structure of the wakefield in a plasma column, produced by a short intense laser pulse, propagating through a gas affected by tunneling ionization is investigated. It is shown that besides the usual plasma waves in the bulk part of the plasma column [see Andreev et al., Phys. Plasmas 9, 3999 (2002)], the laser pulse also generates electromagnetic surface waves propagating along the column boundary. The length of the surface wake wave substantially exceeds the length of the plasma wake wave and its electromagnetic field extends far outside the plasma column
Toric Geometry, Sasaki-Einstein Manifolds and a New Infinite Class of AdS/CFT Duals
Martelli, D; Martelli, Dario; Sparks, James
2006-01-01
Recently an infinite family of explicit Sasaki-Einstein metrics Y^{p,q} on S^2 x S^3 has been discovered, where p and q are two coprime positive integers, with q
The full spectrum of AdS5/CFT4 I: representation theory and one-loop Q-system
Marboe, Christian; Volin, Dmytro
2018-04-01
With the formulation of the quantum spectral curve for the AdS5/CFT4 integrable system, it became potentially possible to compute its full spectrum with high efficiency. This is the first paper in a series devoted to the explicit design of such computations, with no restrictions to particular subsectors being imposed. We revisit the representation theoretical classification of possible states in the spectrum and map the symmetry multiplets to solutions of the quantum spectral curve at zero coupling. To this end it is practical to introduce a generalisation of Young diagrams to the case of non-compact representations and define algebraic Q-systems directly on these diagrams. Furthermore, we propose an algorithm to explicitly solve such Q-systems that circumvents the traditional usage of Bethe equations and simplifies the computation effort. For example, our algorithm quickly obtains explicit analytic results for all 495 multiplets that accommodate single-trace operators in N=4 SYM with classical conformal dimension up to \\frac{13}{2} . We plan to use these results as the seed for solving the quantum spectral curve perturbatively to high loop orders in the next paper of the series.
Confinement near Argyres-Douglas point in N=2 QCD and low energy version of AdS/CFT correspondence
International Nuclear Information System (INIS)
Yung, Alexei
2002-01-01
We study Abrikosov-Nielsen-Olesen (ANO) flux tubes on the Higgs branch of N=2 QCD with SU(2) gauge group and N f =2 flavors of fundamental matter. In particular, we consider this theory near Argyres-Douglas (AD) point where the mass of monopoles connected by these ANO strings become small. In this regime the effective QED which describes the theory on the Higgs branch becomes strongly coupled. We argue that the appropriate description of the theory is in terms of long and thin flux tubes (strings) with small tension. We interpret this as another example of duality between field theory in strong coupling and string theory in weak coupling. Then we consider the non-critical string theory for these flux tubes which includes fifth (Liouville) dimension. We identify CFT at the AD point as UV fix point corresponding to AdS metric on the 5d 'gravity' side. The perturbation associated with the monopole mass term creates a kink separating UV and IR behavior. We estimate the renormalized string tension and show that it is determined by the small monopole mass. In particular, it goes to zero at the AD point
International Nuclear Information System (INIS)
Lin, Shu; Shuryak, Edward
2008-01-01
The equilibration of matter and onset of hydrodynamics can be understood in the AdS/CFT context as a gravitational collapse process, in which 'collision debris' create a horizon. In this paper we consider the simplest geometry possible, a flat shell (or membrane) falling in the holographic direction toward the horizon. The metric is a combination of two well-known solutions: thermal AdS above the shell and pure AdS below, while motion of the shell is given by the Israel junction condition. Furthermore, when the shell motion can be considered slow, we were able to solve for two-point functions of all boundary stress tensors and found that an observer on the boundary sees a very peculiar quasiequilibrium: while the average stress tensor μν> contains the equilibrium plasma energy and pressure at all times, the spectral densities of the correlators (related with occupation probabilities of the modes) reveal additional oscillating terms absent in equilibrium. This is explained by the echo phenomenon, a partial return of the field coherence at certain echo times.
Column: Factors Affecting Data Decay
Directory of Open Access Journals (Sweden)
Kevin Fairbanks
2012-06-01
Full Text Available In nuclear physics, the phrase decay rate is used to denote the rate that atoms and other particles spontaneously decompose. Uranium-235 famously decays into a variety of daughter isotopes including Thorium and Neptunium, which themselves decay to others. Decay rates are widely observed and wildly different depending on many factors, both internal and external. U-235 has a half-life of 703,800,000 years, for example, while free neutrons have a half-life of 611 seconds and neutrons in an atomic nucleus are stable.We posit that data in computer systems also experiences some kind of statistical decay process and thus also has a discernible decay rate. Like atomic decay, data decay fluctuates wildly. But unlike atomic decay, data decay rates are the result of so many different interplaying processes that we currently do not understand them well enough to come up with quantifiable numbers. Nevertheless, we believe that it is useful to discuss some of the factors that impact the data decay rate, for these factors frequently determine whether useful data about a subject can be recovered by forensic investigation.(see PDF for full column
Gaseous carbon dioxide absorbing column
International Nuclear Information System (INIS)
Harashina, Heihachi.
1994-01-01
The absorbing column of the present invention comprises a cyclone to which CO 2 gas and Ca(OH) 2 are blown to form CaCO 3 , a water supply means connected to an upper portion of the cyclone for forming a thin water membrane on the inner wall thereof, and a water processing means connected to a lower portion of the cyclone for draining water incorporating CaCO 3 . If a mixed fluid of CO 2 gas and Ca(OH) 2 is blown in a state where a flowing water membrane is formed on the inner wall of the cyclone, formation of CaCO 3 is promoted also in the inside of the cyclone in addition to the formation of CaCO 3 in the course of blowing. Then, formed CaCO 3 is discharged from the lower portion of the cyclone together with downwardly flowing water. With such procedures, solid contents such as CaCO 3 separated at the inner circumferential wall are sent into the thin water membrane, adsorbed and captured, and the solid contents are successively washed out, so that a phenomenon that the solid contents deposit and grow on the inner wall of the cyclone can be prevented effectively. (T.M.)
Rasch models with exchangeable rows and columns
DEFF Research Database (Denmark)
Lauritzen, Steffen Lilholt
The article studies distributions of doubly infinite binary matrices with exchangeable rows and columns which satify the further property that the probability of any $m \\times n$ submatrix is a function of the row- and column sums of that matrix. We show that any such distribution is a (unique...
The general packed column : an analytical solution
Gielen, J.L.W.
2000-01-01
The transient behaviour of a packed column is considered. The column, uniformly packed on a macroscopic scale, is multi-structured on the microscopic level: the solid phase consists of particles, which may differ in incidence, shape or size, and other relevant physical properties. Transport in the
Fringing-field effects in acceleration columns
International Nuclear Information System (INIS)
Yavor, M.I.; Weick, H.; Wollnik, H.
1999-01-01
Fringing-field effects in acceleration columns are investigated, based on the fringing-field integral method. Transfer matrices at the effective boundaries of the acceleration column are obtained, as well as the general transfer matrix of the region separating two homogeneous electrostatic fields with different field strengths. The accuracy of the fringing-field integral method is investigated
Center column design of the PLT
International Nuclear Information System (INIS)
Citrolo, J.; Frankenberg, J.
1975-01-01
The center column of the PLT machine is a secondary support member for the toroidal field coils. Its purpose is to decrease the bending moment at the nose of the coils. The center column design was to have been a stainless steel casting with the toroidal field coils grouped around the casting at installation, trapping it in place. However, the castings developed cracks during fabrication and were unsuitable for use. Installation of the coils proceeded without the center column. It then became necessary to redesign a center column which would be capable of installation with the toroidal field coils in place. The final design consists of three A-286 forgings. This paper discusses the final center column design and the influence that new knowledge, obtained during the power tests, had on the new design
Admittance Scanning for Whole Column Detection.
Stamos, Brian N; Dasgupta, Purnendu K; Ohira, Shin-Ichi
2017-07-05
Whole column detection (WCD) is as old as chromatography itself. WCD requires an ability to interrogate column contents from the outside. Other than the obvious case of optical detection through a transparent column, admittance (often termed contactless conductance) measurements can also sense changes in the column contents (especially ionic content) from the outside without galvanic contact with the solution. We propose here electromechanically scanned admittance imaging and apply this to open tubular (OT) chromatography. The detector scans across the column; the length resolution depends on the scanning velocity and the data acquisition frequency, ultimately limited by the physical step resolution (40 μm in the present setup). Precision equal to this step resolution was observed for locating an interface between two immiscible liquids inside a 21 μm capillary. Mechanically, the maximum scanning speed was 100 mm/s, but at 1 kHz sampling rate and a time constant of 25 ms, the highest practical scan speed (no peak distortion) was 28 mm/s. At scanning speeds of 0, 4, and 28 mm/s, the S/N for 180 pL (zone length of 1.9 mm in a 11 μm i.d. column) of 500 μM KCl injected into water was 6450, 3850, and 1500, respectively. To facilitate constant and reproducible contact with the column regardless of minor variations in outer diameter, a double quadrupole electrode system was developed. Columns of significant length (>1 m) can be readily scanned. We demonstrate its applicability with both OT and commercial packed columns and explore uniformity of retention along a column, increasing S/N by stopped-flow repeat scans, etc. as unique applications.
Collapse of tall granular columns in fluid
Kumar, Krishna; Soga, Kenichi; Delenne, Jean-Yves
2017-06-01
Avalanches, landslides, and debris flows are geophysical hazards, which involve rapid mass movement of granular solids, water, and air as a multi-phase system. In order to describe the mechanism of immersed granular flows, it is important to consider both the dynamics of the solid phase and the role of the ambient fluid. In the present study, the collapse of a granular column in fluid is studied using 2D LBM - DEM. The flow kinematics are compared with the dry and buoyant granular collapse to understand the influence of hydrodynamic forces and lubrication on the run-out. In the case of tall columns, the amount of material destabilised above the failure plane is larger than that of short columns. Therefore, the surface area of the mobilised mass that interacts with the surrounding fluid in tall columns is significantly higher than the short columns. This increase in the area of soil - fluid interaction results in an increase in the formation of turbulent vortices thereby altering the deposit morphology. It is observed that the vortices result in the formation of heaps that significantly affects the distribution of mass in the flow. In order to understand the behaviour of tall columns, the run-out behaviour of a dense granular column with an initial aspect ratio of 6 is studied. The collapse behaviour is analysed for different slope angles: 0°, 2.5°, 5° and 7.5°.
Field Applications of Gamma Column Scanning Technology
International Nuclear Information System (INIS)
Aquino, Denis D.; Mallilin, Janice P.; Nuñez, Ivy Angelica A.; Bulos, Adelina DM.
2015-01-01
The Isotope Techniques Section (ITS) under the Nuclear Service Division (NSD) of the Philippine Nuclear Research Institute (PNRI) conducts services, research and development on radioisotope and sealed source application in the industry. This aims to benefit the manufacturing industries such as petroleum, petrochemical, chemical, energy, waste, column treatment plant, etc. through on line inspection and troubleshooting of a process vessel, column or pipe that could optimize the process operation and increase production efficiency. One of the most common sealed source techniques for industrial applications is the gamma column scanning technology. Gamma column scanning technology is an established technique for inspection, analysis and diagnosis of industrial columns for process optimization, solving operational malfunctions and management of resources. It is a convenient non-intrusive, cost effective and cost-efficient technique to examine inner details of an industrial process vessel such as a distillation column while it is in operation. The Philippine Nuclear Research Institute (PNRI) recognize the importance and benefits of this technology and has implemented activities to make gamma column scanning locally available to benefit the Philippine industries. Continuous effort for capacity building is being pursued thru the implementation of in-house and on-the-job training abroad and upgrading of equipment. (author)
Dynamic effects of diabatization in distillation columns
DEFF Research Database (Denmark)
Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens
2013-01-01
The dynamic effects of diabatization in distillation columns are investigated in simulation emphasizing the heat-integrated distillation column (HIDiC). A generic, dynamic, first-principle model has been formulated, which is flexible enough to describe various diabatic distillation configurations....... Dynamic Relative Gain Array and Singular Value Analysis have been applied in a comparative study of a conventional distillation column and a HIDiC. The study showed increased input-output coupling due to diabatization. Feasible SISO control structures for the HIDiC were also found and control...
Dynamic Effects of Diabatization in Distillation Columns
DEFF Research Database (Denmark)
Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens
2012-01-01
The dynamic eects of diabatization in distillation columns are investigated in simulation with primary focus on the heat-integrated distillation column (HIDiC). A generic, dynamic, rst-principle model has been formulated, which is exible to describe various diabatic distillation congurations....... Dynamic Relative Gain Array and Singular Value Analysis have been applied in a comparative study of a conventional distillation column and a HIDiC. The study showed increased input-output coupling due to diabatization. Feasible SISO control structures for the HIDiC were also found. Control...
Column-oriented database management systems
Možina, David
2013-01-01
In the following thesis I will present column-oriented database. Among other things, I will answer on a question why there is a need for a column-oriented database. In recent years there have been a lot of attention regarding a column-oriented database, even if the existence of a columnar database management systems dates back in the early seventies of the last century. I will compare both systems for a database management – a colum-oriented database system and a row-oriented database system ...
Family of columns isospectral to gravity-loaded columns with tip force: A discrete approach
Ramachandran, Nirmal; Ganguli, Ranjan
2018-06-01
A discrete model is introduced to analyze transverse vibration of straight, clamped-free (CF) columns of variable cross-sectional geometry under the influence of gravity and a constant axial force at the tip. The discrete model is used to determine critical combinations of loading parameters - a gravity parameter and a tip force parameter - that cause onset of dynamic instability in the CF column. A methodology, based on matrix-factorization, is described to transform the discrete model into a family of models corresponding to weightless and unloaded clamped-free (WUCF) columns, each with a transverse vibration spectrum isospectral to the original model. Characteristics of models in this isospectral family are dependent on three transformation parameters. A procedure is discussed to convert the isospectral discrete model description into geometric description of realistic columns i.e. from the discrete model, we construct isospectral WUCF columns with rectangular cross-sections varying in width and depth. As part of numerical studies to demonstrate efficacy of techniques presented, frequency parameters of a uniform column and three types of tapered CF columns under different combinations of loading parameters are obtained from the discrete model. Critical combinations of these parameters for a typical tapered column are derived. These results match with published results. Example CF columns, under arbitrarily-chosen combinations of loading parameters are considered and for each combination, isospectral WUCF columns are constructed. Role of transformation parameters in determining characteristics of isospectral columns is discussed and optimum values are deduced. Natural frequencies of these WUCF columns computed using Finite Element Method (FEM) match well with those of the given gravity-loaded CF column with tip force, hence confirming isospectrality.
Unbonded Prestressed Columns for Earthquake Resistance
2012-05-01
Modern structures are able to survive significant shaking caused by earthquakes. By implementing unbonded post-tensioned tendons in bridge columns, the damage caused by an earthquake can be significantly lower than that of a standard reinforced concr...
PRTR ion exchange vault column sampling
International Nuclear Information System (INIS)
Cornwell, B.C.
1995-01-01
This report documents ion exchange column sampling and Non Destructive Assay (NDA) results from activities in 1994, for the Plutonium Recycle Test Reactor (PRTR) ion exchange vault. The objective was to obtain sufficient information to prepare disposal documentation for the ion exchange columns found in the PRTR Ion exchange vault. This activity also allowed for the monitoring of the liquid level in the lower vault. The sampling activity contained five separate activities: (1) Sampling an ion exchange column and analyzing the ion exchange media for purpose of waste disposal; (2) Gamma and neutron NDA testing on ion exchange columns located in the upper vault; (3) Lower vault liquid level measurement; (4) Radiological survey of the upper vault; and (5) Secure the vault pending waste disposal
International Nuclear Information System (INIS)
Liu Limin; Wang Yong; Li Bo; Jia Jun; Sun Zuoli; Zhang Jinming; Tian Jiahe; Wang Xiaomin
2009-01-01
Introduction: The cardinal pathological feature of Parkinson's disease (PD) is progressive loss of dopaminergic neurons. Since dopamine transporter (DAT) is a protein located presynaptically on dopaminergic nerve terminals, radioligands that bind to these sites are promising radiopharmaceuticals for evaluation of the integrity of the dopamine system. This study using positron emission tomography (PET) tracers, [ 11 C]-2β-carbomethoxy-3β-(4-fluorophenyl)-tropane ([ 11 C]β-CFT, radioligand for DAT), was aimed at evaluating the degree of nigrostriatal damage and its change over weeks in a rat model of PD. Methods: The brains of these rats were unilaterally lesioned by mechanical transection of the nigrostriatal dopamine pathway at the medial forebrain bundle (MFB). Behavioral studies were carried out by apomorphine (APO) challenge prior to and 1, 2 and 4 weeks after MFB axotomy. Small animal PET scans were performed 2 days after the behavioral test. Immunohistochemistry was conducted 4 days after the last PET scan. Results: Compared with the contralateral intact side, a progressively decreased [ 11 C]β-CFT binding was observed on the lesioned side which correlated inversely with the APO-induced rotations. Postmortem immunohistochemical studies confirmed the loss of both striatal dopamine fibers and nigral neurons on the lesioned side. Conclusion: These findings not only demonstrate that the neuronal degeneration in this model is relatively slow, but also suggest [ 11 C]β-CFT is a sensitive marker to monitor the degree of nigrostriatal damage and its change over weeks. This marker can be used prospectively to study the progression of the disease, thereby making detection of early phases of PD possible.
Capacity of columns with splice imperfections
International Nuclear Information System (INIS)
Popov, E.P.; Stephen, R.M.
1977-01-01
To study the behavior of spliced columns subjected to tensile forces simulating situations which may develop in an earthquake, all of the spliced specimens were tested to failure in tension after first having been subjected to large compressive loads. The results of these tests indicate that the lack of perfect contact at compression splices of columns may not be important, provided that the gaps are shimmed and welding is used to maintain the sections in alignment
Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column
Huz, Kateryna
2014-01-01
RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better
The handedness of historiated spiral columns.
Couzin, Robert
2017-09-01
Trajan's Column in Rome (AD 113) was the model for a modest number of other spiral columns decorated with figural, narrative imagery from antiquity to the present day. Most of these wind upwards to the right, often with a congruent spiral staircase within. A brief introductory consideration of antique screw direction in mechanical devices and fluted columns suggests that the former may have been affected by the handedness of designers and the latter by a preference for symmetry. However, for the historiated columns that are the main focus of this article, the determining factor was likely script direction. The manner in which this operated is considered, as well as competing mechanisms that might explain exceptions. A related phenomenon is the reversal of the spiral in a non-trivial number of reproductions of the antique columns, from Roman coinage to Renaissance and baroque drawings and engravings. Finally, the consistent inattention in academic literature to the spiral direction of historiated columns and the repeated publication of erroneous earlier reproductions warrants further consideration.
Interpretation of the lime column penetration test
International Nuclear Information System (INIS)
Liyanapathirana, D S; Kelly, R B
2010-01-01
Dry soil mix (DSM) columns are used to reduce the settlement and to improve the stability of embankments constructed on soft clays. During construction the shear strength of the columns needs to be confirmed for compliance with technical assumptions. A specialized blade shaped penetrometer known as the lime column probe, has been developed for testing DSM columns. This test can be carried out as a pull out resistance test (PORT) or a push in resistance test (PIRT). The test is considered to be more representative of average column shear strength than methods that test only a limited area of the column. Both PORT and PIRT tests require empirical correlations of measured resistance to an absolute measure of shear strength, in a similar manner to the cone penetration test. In this paper, finite element method is used to assess the probe factor, N, for the PORT test. Due to the large soil deformations around the probe, an Arbitrary Lagrangian Eulerian (ALE) based finite element formulation has been used. Variation of N with rigidity index and the friction at the probe-soil interface are investigated to establish a range for the probe factor.
Energy Technology Data Exchange (ETDEWEB)
Busigin, A. [NITEK USA Inc., Ocala, FL (United States)
2015-03-15
Liquid Phase Catalytic Exchange (LPCE) is a key technology used in water detritiation systems. Rigorous simulation of LPCE is complicated when a column may have both hydrogen and deuterium present in significant concentrations in different sections of the column. This paper presents a general mass transfer model for a homogenous packed bed LPCE column as a set of differential equations describing composition change, and equilibrium equations to define the mass transfer driving force within the column. The model is used to show the effect of deuterium buildup in the bottom of an LPCE column from non-negligible D atom fraction in the bottom feed gas to the column. These types of calculations are important in the design of CECE (Combined Electrolysis and Catalytic Exchange) water detritiation systems.
International Nuclear Information System (INIS)
Miura, Hidenori; Uozumi, Koichi
2009-01-01
At electrorefining process, fission products(FPs) accumulate in molten salt. To avoid influence on heating control by decay heat and enlargement of FP amount in the recovered fuel, FP elements must be removed from the spent salt of the electrorefining process. For the removal of the FPs from the spent salt, we are investigating the availability of zeolite column system. For obtaining the basic data of the column system, such as flow property and ion-exchange performance while high temperature molten salt is passing through the column, and experimental apparatus equipped with fraction collector was developed. By using this apparatus, following results were obtained. 1) We cleared up the flow parameter of column system with zeolite powder, such as flow rate control by argon pressure. 2) Zeolite 4A in the column can absorb cesium that is one of the FP elements in molten salt. From these results, we got perspective on availability of the zeolite column system. (author)
Structural Decoupling and Disturbance Rejection in a Distillation Column
DEFF Research Database (Denmark)
Bahar, Mehrdad; Jantzen, Jan; Commault, C.
1996-01-01
Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references.......Introduction, distillation column model, input-output decoupling, disturbance rejection, concluding remarks, references....
Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz
2016-01-21
This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.
Recent advances in column switching sample preparation in bioanalysis.
Kataoka, Hiroyuki; Saito, Keita
2012-04-01
Column switching techniques, using two or more stationary phase columns, are useful for trace enrichment and online automated sample preparation. Target fractions from the first column are transferred online to a second column with different properties for further separation. Column switching techniques can be used to determine the analytes in a complex matrix by direct sample injection or by simple sample treatment. Online column switching sample preparation is usually performed in combination with HPLC or capillary electrophoresis. SPE or turbulent flow chromatography using a cartridge column and in-tube solid-phase microextraction using a capillary column have been developed for convenient column switching sample preparation. Furthermore, various micro-/nano-sample preparation devices using new polymer-coating materials have been developed to improve extraction efficiency. This review describes current developments and future trends in novel column switching sample preparation in bioanalysis, focusing on innovative column switching techniques using new extraction devices and materials.
Contributions to reversed-phase column selectivity: III. Column hydrogen-bond basicity.
Carr, P W; Dolan, J W; Dorsey, J G; Snyder, L R; Kirkland, J J
2015-05-22
Column selectivity in reversed-phase chromatography (RPC) can be described in terms of the hydrophobic-subtraction model, which recognizes five solute-column interactions that together determine solute retention and column selectivity: hydrophobic, steric, hydrogen bonding of an acceptor solute (i.e., a hydrogen-bond base) by a stationary-phase donor group (i.e., a silanol), hydrogen bonding of a donor solute (e.g., a carboxylic acid) by a stationary-phase acceptor group, and ionic. Of these five interactions, hydrogen bonding between donor solutes (acids) and stationary-phase acceptor groups is the least well understood; the present study aims at resolving this uncertainty, so far as possible. Previous work suggests that there are three distinct stationary-phase sites for hydrogen-bond interaction with carboxylic acids, which we will refer to as column basicity I, II, and III. All RPC columns exhibit a selective retention of carboxylic acids (column basicity I) in varying degree. This now appears to involve an interaction of the solute with a pair of vicinal silanols in the stationary phase. For some type-A columns, an additional basic site (column basicity II) is similar to that for column basicity I in primarily affecting the retention of carboxylic acids. The latter site appears to be associated with metal contamination of the silica. Finally, for embedded-polar-group (EPG) columns, the polar group can serve as a proton acceptor (column basicity III) for acids, phenols, and other donor solutes. Copyright © 2015 Elsevier B.V. All rights reserved.
ON THE ORIGIN OF THE HIGH COLUMN DENSITY TURNOVER IN THE H I COLUMN DENSITY DISTRIBUTION
International Nuclear Information System (INIS)
Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.
2012-01-01
We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ≈ 10 21 cm –2 , which is present at both z = 0 and z ≈ 3, and a lack of systems above N H I ≈ 10 22 cm –2 at z = 0. Using observations of the column density distribution, we argue that the H I-H 2 transition does not cause the turnover at N H I ≈ 10 21 cm –2 but can plausibly explain the turnover at N H I ∼> 10 22 cm –2 . We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Lyα column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ∼ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.
A stochastic view on column efficiency.
Gritti, Fabrice
2018-03-09
A stochastic model of transcolumn eddy dispersion along packed beds was derived. It was based on the calculation of the mean travel time of a single analyte molecule from one radial position to another. The exchange mechanism between two radial positions was governed by the transverse dispersion of the analyte across the column. The radial velocity distribution was obtained by flow simulations in a focused-ion-beam scanning electron microscopy (FIB-SEM) based 3D reconstruction from a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 particles. Accordingly, the packed bed was divided into three coaxial and uniform zones: (1) a 1.4 particle diameter wide, ordered, and loose packing at the column wall (velocity u w ), (2) an intermediate 130 μm wide, random, and dense packing (velocity u i ), and (3) the bulk packing in the center of the column (velocity u c ). First, the validity of this proposed stochastic model was tested by adjusting the predicted to the observed reduced van Deemter plots of a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 fully porous particles (FPPs). An excellent agreement was found for u i = 0.93u c , a result fully consistent with the FIB-SEM observation (u i = 0.95u c ). Next, the model was used to measure u i = 0.94u c for 2.1 mm × 100 mm column packed with 1.6 μm Cortecs-C 18 superficially porous particles (SPPs). The relative velocity bias across columns packed with SPPs is then barely smaller than that observed in columns packed with FPPs (+6% versus + 7%). u w =1.8u i is measured for a 75 μm × 1 m capillary column packed with 2 μm BEH-C 18 particles. Despite this large wall-to-center velocity bias (+80%), the presence of the thin and ordered wall packing layer has no negative impact on the kinetic performance of capillary columns. Finally, the stochastic model of long-range eddy dispersion explains why analytical (2.1-4.6 mm i.d.) and capillary (columns can all be
Vertebral Column Resection for Rigid Spinal Deformity.
Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G
2017-05-01
Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.
Effect of backmixing on pulse column performance
International Nuclear Information System (INIS)
Miao, Y.W.
1979-05-01
A critical survey of the published literature concerning dispersed phase holdup and longitudinal mixing in pulsed sieve-plate extraction columns has been made to assess the present state-of-the-art in predicting these two parameters, both of which are of critical importance in the development of an accurate mathematical model of the pulse column. Although there are many conflicting correlations of these variables as a function of column geometry, operating conditions, and physical properties of the liquid systems involved it has been possible to develop new correlations which appear to be useful and which are consistent with much of the available data over the limited range of variables most likely to be encountered in plant sized equipment. The correlations developed were used in a stagewise model of the pulse column to predict product concentrations, solute inventory, and concentration profiles in a column for which limited experimental data were available. Reasonable agreement was obtained between the mathematical model and the experimental data. Complete agreement, however, can only be obtained after a correlation for the extraction efficiency has been developed. The correlation of extraction efficiency was beyond the scope of this work
International Nuclear Information System (INIS)
Qiu Chun; Zuo Chuantao; Zhang Zhengwei; Wu Ping; Zhang Huiwei; Guan Yihui
2013-01-01
Objective: To find the optimal scanning time window and then set up the normal binding potentials (BPs) of 2β-carbomethoxy-3β-(4-fluorophenyl)-(N- 11 C-methyl) tropane ( 11 C-CFT) DAT PET/CT imaging. Methods: Thirty-one healthy volunteers (20 males, 11 females, average age: (55.7±2.3) years), who all gave written informed consent, were divided into three age and gender-matched groups according to block randomization. Each group underwent static PET/CT scan in different time windows from 40-60 min, 60-80 min to 80-100 min after 11 C-CFT injection. To determine the best scanning time window, the ratios of caudate and putamen of all volunteers were analyzed using automatic ROI method (caudate (putamen)/parieto-occipital cotex-1) and compared by one-way analysis of variance and the least significant difference (LSD) t test. The ratio of the same area between different age-groups and gender-groups was compared with independent two-sample t test. Results: Ratios of left caudate (2.08±0.06, 1.75±0.07 and 1.77±0.12 respectively), right anterior putamen (2.33±0.06, 1.95±0.09 and 2.08±0.12 respectively) and bilateral posterior putamen (left: 1.88±0.66, 1.55±0.88 and 1.72±0.09; right: 1.98±0.07, 1.61±0.09 and 1.69±0.12) were all different in three time windows (F=3.588, 3.345, 4.479, 3.557, all P<0.05). There were significant differences in ratios of left caudate, right anterior and bilateral posterior putamen between 40-60 min and the 60-80 min (all P<0.05), as well as the ratios of left caudate between 40-60 min and the 80-100 min group (P<0.05). While no valid differences in ratios of those areas were shown between the groups of 60-80 min and 80-100 min scanning time window (all P>0.05). DAT densities in right and left side of caudate, anterior and posterior putamen were significantly lower in the group over 60 years of age than those under 60 years (t=-3.260, -3.090, -3.270, -3.190, -2.270, -3.110, all P<0.05), but were not different between gender
Mathematical modeling of alcohol distillation columns
Directory of Open Access Journals (Sweden)
Ones Osney Pérez
2011-04-01
Full Text Available New evaluation modules are proposed to extend the scope of a modular simulator oriented to the sugar cane industry, called STA 4.0, in a way that it can be used to carry out x calculation and analysis in ethanol distilleries. Calculation modules were developed for the simulation of the columns that are combined in the distillation area. Mathematical models were supported on materials and energy balances, equilibrium relations and thermodynamic properties of the ethanol-water system. Ponchon-Savarit method was used for the evaluation of the theoretical stages in the columns. A comparison between the results using Ponchon- Savarit method and those obtained applying McCabe-Thiele method was done for a distillation column. These calculation modules for ethanol distilleries were applied to a real case for validation.
Inert carriers for column extraction chromatography
International Nuclear Information System (INIS)
Katykhin, G.S.
1978-01-01
Inert carriers used in column extraction chromatography are reviewed. Such carriers are devided into two large groups: hydrophilic carriers which possess high surface energy and are well wetted only with strongly polar liquids (kieselguhrs, silica gels, glasses, cellulose, Al 2 O 3 ) and water-repellent carriers which possess low surface energy and are well wetted with various organic solvents (polyethylene, polytetrafluorethylene polytrifluorochlorethylene). Properties of various carriers are presented: structure, chemical and radiation stability, adsorption properties, extracting agent capacity. The effect of structure and sizes of particles on the efficiency of chromatography columns is considered. Ways of immovable phase deposition on the carrier and the latter's regeneration. Peculiarities of column packing for preparative and continuous chromatography are discussed
Computational analysis of ozonation in bubble columns
International Nuclear Information System (INIS)
Quinones-Bolanos, E.; Zhou, H.; Otten, L.
2002-01-01
This paper presents a new computational ozonation model based on the principle of computational fluid dynamics along with the kinetics of ozone decay and microbial inactivation to predict the performance of ozone disinfection in fine bubble columns. The model can be represented using a mixture two-phase flow model to simulate the hydrodynamics of the water flow and using two transport equations to track the concentration profiles of ozone and microorganisms along the height of the column, respectively. The applicability of this model was then demonstrated by comparing the simulated ozone concentrations with experimental measurements obtained from a pilot scale fine bubble column. One distinct advantage of this approach is that it does not require the prerequisite assumptions such as plug flow condition, perfect mixing, tanks-in-series, uniform radial or longitudinal dispersion in predicting the performance of disinfection contactors without carrying out expensive and tedious tracer studies. (author)
Energy Technology Data Exchange (ETDEWEB)
Rastelli, Leonardo [C.N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY (United States)
2016-04-15
This contribution collects background material and references for the overview talk that was delivered in the 21st European string workshop and 3rd COST MP1210 meeting, 'The String Theory Universe'. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
CUB DI (Deionization) column control system
International Nuclear Information System (INIS)
Seino, K.C.
1999-01-01
For the old MR (Main Ring), deionization was done with two columns in CUB, using an ion exchange process. Typically 65 GPM of LCW flew through a column, and the resistivity was raised from 3 Mohm-cm to over 12 Mohm-cm. After a few weeks, columns lost their effectiveness and had to be regenerated in a process involving backwashing and adding hydrochloric acid and sodium hydroxide. For normal MR operations, LCW returned from the ring and passed through the two columns in parallel for deionization, although the system could have been operated satisfactorily with only one in use. A 3000 gallon reservoir (the Spheres) provided a reserve of LCW for allowing water leaks and expansions in the MR. During the MI (Main Injector) construction period, the third DI column was added to satisfy requirements for the MI. When the third column was added, the old regeneration controller was replaced with a new controller based on an Allen-Bradley PLC (i.e., SLC-5/04). The PLC is widely used and well documented, and therefore it may allow us to modify the regeneration programs in the future. In addition to the above regeneration controller, the old control panels (which were used to manipulate pumps and valves to supply LCW in Normal mode and to do Int. Recir. (Internal Recirculation) and Makeup) were replaced with a new control system based on Sixtrak Gateway and I/O modules. For simplicity, the new regeneration controller is called as the US Filter system, and the new control system is called as the Fermilab system in this writing
Operation of the annular pulsed column, (2)
International Nuclear Information System (INIS)
Takahashi, Keiki; Tsukada, Takeshi
1988-01-01
The heat of reaction generated form the uranium extraction is considered to from the temperature profile inside the pulsed column. A simulation code was developed to estimate the temperature profile, considering heat generation and counter-current heat transfer. The temperature profiles calculated using this code was found to depend on both the position of the extraction zone and the operating condition. The reported experimental result was fairly represented by this simulation code. We consider that this presented simulation code is capable of providing with the temperature profile in the pulsed column and useful for the monitoring of the uranium extraction zone. (author)
Distillation columns inspection through gamma scanning
International Nuclear Information System (INIS)
Garcia, Marco
1999-09-01
The application of nuclear energy is very wide and it allows the saving of economic resources since the investigation of a certain process is carried out without stop the plant. The gamma scanning of oil c racking c olumns are practical examples, they allow to determine the hydraulic operation of the inspected columns. A source of Co-60 22mCi and a detector with a crystal of INa(TI) are used. This paper shows the results got from a profile carried out in a column distillation
Performance of RC columns with partial length corrosion
International Nuclear Information System (INIS)
Wang Xiaohui; Liang Fayun
2008-01-01
Experimental and analytical studies on the load capacity of reinforced concrete (RC) columns with partial length corrosion are presented, where only a fraction of the column length was corroded. Twelve simply supported columns were eccentrically loaded. The primary variables were partial length corrosion in tensile or compressive zone and the corrosion level within this length. The failure of the corroded column occurs in the partial length, mainly developed from or located nearby or merged with the longitudinal corrosion cracks. For RC column with large eccentricity, load capacity of the column is mainly influenced by the partial length corrosion in tensile zone; while for RC column with small eccentricity, load capacity of the column greatly decreases due to the partial length corrosion in compressive zone. The destruction of the longitudinally mechanical integrality of the column in the partial length leads to this great reduction of the load capacity of the RC column
Directory of Open Access Journals (Sweden)
Achoura D.
2012-09-01
Full Text Available Dans cette étude, on présente les résultats expérimentaux obtenus sur des poteaux mixtes béton-acier mince réalisés par soudures. Un total de 24 profilés en acier, et en forme de I a été testé sous charge de compression uni-axiale à l’âge de 28 jours. les spécimens ont été réparties comme suit: 4 à vides, 4 partiellement remplies avec un béton ordinaire sans l’addition des connecteurs, 4 renforcés par des connecteurs de cisaillements de type cornière en U, 4 autres l’ont été avec des connecteurs de cisaillements type goujons et 8 restants ont été renforcés avec des liens transversaux d’espacement 100mm, 50mm, soudés aux bouts des ailes opposées. Les principaux paramètres étudiés sont: l’élancement du profilé, le type de connecteur de renforcement. A partir des résultats d’essais obtenus, il est confirmé que les parois minces sont plus sensibles de l’apparition au voilement et la longueur des profilés a un effet considérable sur la capacité portante et le mode de rupture. L’addition des connecteurs de renforcement a confirmé l’augmentation de la charge ultime par rapport aux profilés sans connecteurs. In the present work, results of tests conducted on thin welded steel-concrete stubs are presented. A total of 24 stubs an I steel section were tested under axial compression at 28 days after the date of casting, 4 were empty, 4 filled with normal concrete, 8 columns had shear connecters welded along the centreline of the web, and 8 columns had steel rods welded between the tips of opposing flanges on both sides of the spacing of the transverse link 100 mm and 50 mm. The main parameters studied were: the heel height, and type of connector strengthening. From the test results, it is confirmed that the thin walls are more sensitive to the appearance local buckling and the length of the profiles has a significant effect on the bearing capacity and failure mode. The bearing capacity was increased
Schweiger, Susanne; Jungbauer, Alois
2018-02-16
Small pre-packed columns are commonly used to estimate the optimum run parameters for pilot and production scale. The question arises if the experiments obtained with these columns are scalable, because there are substantial changes in extra column volume when going from a very small scale to a benchtop column. In this study we demonstrate the scalability of pre-packed disposable and non-disposable columns of volumes in the range of 0.2-20 ml packed with various media using superficial velocities in the range of 30-500 cm/h. We found that the relative contribution of extra column band broadening to total band broadening was not only high for columns with small diameters, but also for columns with a larger volume due to their wider diameter. The extra column band broadening can be more than 50% for columns with volumes larger than 10 ml. An increase in column diameter leads to high additional extra column band broadening in the filter, frits, and adapters of the columns. We found a linear relationship between intra column band broadening and column length, which increased stepwise with increases in column diameter. This effect was also corroborated by CFD simulation. The intra column band broadening was the same for columns packed with different media. An empirical engineering equation and the data gained from the extra column effects allowed us to predict the intra, extra, and total column band broadening just from column length, diameter, and flow rate. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.
Convolutional Codes with Maximum Column Sum Rank for Network Streaming
Mahmood, Rafid; Badr, Ahmed; Khisti, Ashish
2015-01-01
The column Hamming distance of a convolutional code determines the error correction capability when streaming over a class of packet erasure channels. We introduce a metric known as the column sum rank, that parallels column Hamming distance when streaming over a network with link failures. We prove rank analogues of several known column Hamming distance properties and introduce a new family of convolutional codes that maximize the column sum rank up to the code memory. Our construction invol...
Wang, Chunlei; Tymiak, Adrienne A; Zhang, Yingru
2014-04-15
Tandem column supercritical fluid chromatography (SFC) has demonstrated to be a useful technique to resolve complex mixtures by serially coupling two columns of different selectivity. The overall selectivity of a tandem column separation is the retention time weighted average of selectivity from each coupled column. Currently, the method development merely relies on extensive screenings and is often a hit-or-miss process. No attention is paid to independently adjust retention and selectivity contributions from individual columns. In this study, we show how tandem column SFC selectivity can be optimized by changing relative dimensions (length or inner diameter) of the coupled columns. Moreover, we apply column back pressure as a unique parameter for SFC optimization. Continuous tuning of tandem column SFC selectivity is illustrated through column back pressure adjustments of the upstream column, for the first time. In addition, we show how and why changing coupling order of the columns can produce dramatically different separations. Using the empirical mathematical equation derived in our previous study, we also demonstrate a simulation of tandem column separations based on a single retention time measurement on each column. The simulation compares well with experimental results and correctly predicts column order and back pressure effects on the separations. Finally, considerations on instrument and column hardware requirements are discussed.
Park, Y.; Hou, L.; Atwill, R.; Packman, A. I.; Harter, T.
2009-12-01
Cryptosporidium is one of the most common enteric parasites of humans and domestic animals, and a number of outbreaks of Cryprosporidiosis, a diarrheal disease caused by Cryptosporidium have been reported worldwide. Natural porous media has been demonstrated to be an effective filter for removing Cryptosporidium parvum from contaminated water and the amount of Cryptosporidium filtered is known to be highly dependent on physical and chemical conditions of the porous media and the water. Cryptosporidium deposition in saturated porous media involves two main steps: approach and attachment. In contrast to the approach mechanisms, attachment processes have not been systematically described to predict a priori because theories that represent attachment behavior (colloid stability) such as DLVO are insufficient to explain experimental data. For this reason, attachment efficiency is calculated based on empirical data, typically experimental breakthrough curves in laboratory columns or field experiments. In this study, collision (attachment) efficiencies (α) of C. parvum oocyst were calculated to test the effect of chemical property changes on the association of oocysts with sand grains. The breakthrough curve data obtained from twelve column experiments and three models were employed to calculate single collector efficiency (η) and α. The first ten experiments were conducted by changing ionic strength and pH, and mixing with natural sediments under the same physical properties (same η). Our experiment results show that iron coating or clay/suspended solids mixture drastically enhanced oocyst deposition. The experiments also showed that increase in ionic strength and decrease in pH enhanced the attachment efficiency. However, the experiment with 100mM NaCl resulted in low attachment efficiency and the experiment with pH 8.5 showed similar attachment efficiency to the one at pH 7. Based on the results from two additional experiments with different flow velocities, it
Influence of pressure on the properties of chromatographic columns. II. The column hold-up volume.
Gritti, Fabrice; Martin, Michel; Guiochon, Georges
2005-04-08
The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C18-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C18 (10% carbon) and the Symmetry-C18 (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C18-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.
Pulsing flow in trickle bed columns
Blok, Jan Rudolf
1981-01-01
In the operation of a packed column with cocurrent downflow of gas and liquid (trickle bed) several flowpatterns can be observed depending on the degree of interaction between gas and liquid. At low liquid and gas flow rates - low interaction - gascontinuous flow occurs. In this flowregime, the
Revive your columns with cyclic distillation
Kiss, Anton A.; Bîldea, Costin Sorin
2015-01-01
The process intensification (PI) technique involves changing a tower?s internals and operating mode and the separate movement of the liquid and vapor phases. This can significantly increase column throughput and reduce energy requirements, while improving separation performance. PI is a set of
Robust Geometric Control of a Distillation Column
DEFF Research Database (Denmark)
Kymmel, Mogens; Andersen, Henrik Weisberg
1987-01-01
A frequency domain method, which makes it possible to adjust multivariable controllers with respect to both nominal performance and robustness, is presented. The basic idea in the approach is that the designer assigns objectives such as steady-state tracking, maximum resonance peaks, bandwidth, m...... is used to examine and improve geometric control of a binary distillation column....
Khalili, Parviz
2009-01-01
We will prove a well-known theorem in Linear Algebra, that is, for any "m x n" matrix the dimension of row space and column space are the same. The proof is based on the subject of "elementary matrices" and "reduced row-echelon" form of a matrix.
On Stability of a Bubble Column
Czech Academy of Sciences Publication Activity Database
Růžička, Marek
2013-01-01
Roč. 91, č. 2 (2013), s. 191-203 ISSN 0263-8762 R&D Projects: GA ČR GA104/07/1110 Institutional support: RVO:67985858 Keywords : bubble column * flow regimes * steady solution Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.281, year: 2013
Thermal Analysis of LANL Ion Exchange Column
International Nuclear Information System (INIS)
Laurinat, J.E.
1999-01-01
This document reports results from an ion exchange column heat transfer analysis requested by Los Alamos National Laboratory (LANL). The object of the analysis is to demonstrate that the decay heat from the Pu-238 will not cause resin bed temperatures to increase to a level where the resin significantly degrades
Column Stores as an IR Prototyping Tool
H.F. Mühleisen (Hannes); T. Samar (Thaer); J.J.P. Lin (Jimmy); A.P. de Vries (Arjen)
2014-01-01
textabstract. We make the suggestion that instead of implementing custom index structures and query evaluation algorithms, IR researchers should simply store document representations in a column-oriented relational database and write ranking models using SQL. For rapid prototyping, this is
Single column and two-column H-D-T distillation experiments at TSTA
International Nuclear Information System (INIS)
Yamanishi, T.; Yoshida, H.; Hirata, S.; Naito, T.; Naruse, Y.; Sherman, R.H.; Bartlit, J.R.; Anderson, J.L.
1988-01-01
Cryogenic distillation experiments were peformed at TSTA with H-D-T system by using a single column and a two-column cascade. In the single column experiment, fundamental engineering data such as the liquid holdup and the HETP were measured under a variety of operational condtions. The liquid holdup in the packed section was about 10 /approximately/ 15% of its superficial volume. The HETP values were from 4 to 6 cm, and increased slightly with the vapor velocity. The reflux ratio had no effect on the HETP. For the wo-colunn experiemnt, dynamic behavior of the cascade was observed. 8 refs., 7 figs., 2 tabs
The central column structure in SPHEX
International Nuclear Information System (INIS)
Duck, R.C.; French, P.A.; Browning, P.K.; Cunningham, G.; Gee, S.J.; al-Karkhy, A.; Martin, R.; Rusbridge, M.G.
1994-01-01
SPHEX is a gun injected spheromak in which a magnetised Marshall gun generates and maintains an approximately axisymmetric toroidal plasma within a topologically spherical flux conserving vessel. The central column has been defined as a region of high mean floating potential, f > up to ∼ 150 V, aligned with the geometric axis of the device. It has been suggested that this region corresponds to the open magnetic flux which is connected directly to the central electrode of the gun and links the toroidal annulus (in which f > ∼ 0 V). Poynting vector measurements have shown that the power required to drive toroidal current in the annulus is transmitted out of the column by the coherent 20 kHz mode which pervades the plasma. Measurements of the MHD dynamo in the column indicate an 'antidynamo' electric field due to correlated fluctuations in v and B at the 20 kHz mode frequency which is consistent with the time-averaged Ohm's Law. On shorting the gun electrodes, the density in the column region decays rapidly leaving a 'hole' of radius R c ∼ 7 cm. This agrees with the estimated dimension of the open flux from mean internal B measurements and axisymmetric force-free equilibrium modelling, but is considerably smaller than the radius of ∼ 13 cm inferred from the time-averaged potential. In standard operating conditions the gun delivers a current of I G ∼ 60 kA at V G ∼ 500 V for ∼ 1 ms, driving a toroidal current of I t ∼ 60 kA. Ultimately we wish to understand the mechanism which drives toroidal current in the annulus; the central column is of interest because of the crucial role it plays in this process. (author) 8 refs., 6 figs
Column, particularly extraction column, for fission and/or breeder materials
International Nuclear Information System (INIS)
Vietzke, H.; Pirk, H.
1980-01-01
An absorber rod with a B 4 C insert is situated in the long extraction column for a uranyl nitrate solution or a plutonium nitrate solution. The geometrical dimensions are designed for a high throughput with little corrosion. (DG) [de
Extensive numerical study of a D-brane, anti-D-brane system in AdS{sub 5}/CFT{sub 4}
Energy Technology Data Exchange (ETDEWEB)
Hegedűs, Árpád [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary)
2015-04-20
In this paper the hybrid-NLIE approach of http://dx.doi.org/10.1007/JHEP08(2012)022 is extended to the ground state of a D-brane anti-D-brane system in AdS/CFT. The hybrid-NLIE equations presented in the paper are finite component alternatives of the previously proposed TBA equations and they admit an appropriate framework for the numerical investigation of the ground state of the problem. Straightforward numerical iterative methods fail to converge, thus new numerical methods are worked out to solve the equations. Our numerical data confirm the previous TBA data. In view of the numerical results the mysterious L=1 case is also commented in the paper.
DEFF Research Database (Denmark)
Hancock, Viktoria; Vejborg, Rebecca Munk; Klemm, Per
2010-01-01
Strain CFT073 is a bona fide uropathogen, whereas strains 83972 and Nissle 1917 are harmless probiotic strains of urinary tract and faecal origin, respectively. Despite their different environmental origins and dispositions the three strains are very closely related and the ancestors of 83972...... of the three strains are closely related. The data demonstrate that the distance from a pathogen to a probiotic strain can be surprisingly short. We demonstrate that Nissle 1917, in spite of its intestinal niche origin, grows well in urine, and is a good biofilm former in this medium in which it also out...... accounting for the impaired biofilm formation. Although the three strains have very different strategies vis-à-vis the human host their functional gene profiles are surprisingly similar. It is also interesting to note that the only two Escherichia coli strains used as probiotics are in fact deconstructed...
HETP evaluation of structured packing distillation column
Directory of Open Access Journals (Sweden)
A. E. Orlando Jr.
2009-09-01
Full Text Available Several tests with a hydrocarbon mixture of known composition (C8-C14, obtained from DETEN Chemistry S.A., have been performed in a laboratory distillation column, having 40mm of nominal diameter and 2.2m high, with internals of Sulzer DX gauze stainless steel structured packing. The main purpose of this work was to evaluate HETP of a structured packing laboratory scale distillation column, operating continuously. Six HETP correlations available in the literature were compared in order to find out which is the most appropriate for structured packing columns working with medium distillates. Prior to the experimental tests, simulation studies using commercial software PRO/II® were performed in order to establish the optimum operational conditions for the distillation, especially concerning operating pressure, top and bottom temperatures, feed location and reflux ratio. The results of PRO/II® were very similar to the analysis of the products obtained during continuous operation, therefore permitting the use of the properties calculated by that software on the theoretical models investigated. The theoretical models chosen for HETP evaluation were: Bravo, Rocha and Fair (1985; Rocha, Bravo and Fair (1993, 1996; Brunazzi and Pagliant (1997; Carlo, Olujić and Pagliant (2006; Olujić et al., (2004. Modifications concerning calculation of specific areas were performed on the correlations in order to fit them for gauze packing HETP evaluation. As the laboratory distillation column was operated continuously, different HETP values were found by the models investigated for each section of the column. The low liquid flow rates in the top section of the column are a source of error for HETP evaluation by the models; therefore, more reliable HETP values were found in the bottom section, in which liquid flow rates were much greater. Among the theoretical models, Olujić et al. (2004 has shown good results relative to the experimental tests. In addition, the
Supergravity one-loop corrections on AdS7 and AdS3, higher spins and AdS/CFT
Directory of Open Access Journals (Sweden)
Matteo Beccaria
2015-03-01
Full Text Available As was shown earlier, the one-loop correction in 10d supergravity on AdS5×S5 corresponds to the contributions to the vacuum energy and 4d boundary conformal anomaly which are minus the values for one N=4 Maxwell supermultiplet, thus reproducing the subleading term in the N2−1 coefficient in the dual SU(N SYM theory. We perform similar one-loop computations in 11d supergravity on AdS7×S4 and 10d supergravity on AdS3×S3×T4. In the AdS7 case we find that the corrections to the 6d conformal anomaly a-coefficient and the vacuum energy are again minus the ones for one (2,0 tensor multiplet, suggesting that the total a-anomaly coefficient for the dual (2,0 theory is 4N3−9/4N−7/4 and thus vanishes for N=1. In the AdS3 case the one-loop correction to the vacuum energy or 2d central charge turns out to be equal to that of one free (4,4 scalar multiplet, i.e. is c=+6. This reproduces the subleading term in the central charge c=6(Q1Q5+1 of the dual 2d CFT describing decoupling limit of D5–D1 system. We also present the expressions for the 6d a-anomaly coefficient and vacuum energy contributions of general-symmetry higher spin field in AdS7 and consider their application to tests of vectorial AdS/CFT with the boundary conformal 6d theory represented by free scalars, spinors or rank-2 antisymmetric tensors.
Mitigating oil spills in the water column
International Nuclear Information System (INIS)
Barry, Edward; Libera, Joseph A.; Mane, Anil University; Avila, Jason R.; DeVitis, David
2017-01-01
The scale and scope of uncontrolled oil spills can be devastating. Diverse marine environments and fragile ecologies are some of the most susceptible to the many ill effects, while the economic costs can be crippling. A notoriously difficult challenge with no known technological solution is the successful removal of oil dispersed in the water column. Here, we address this problem through cheap and reusable oil sorbents based on the chemical modification of polymer foams. Interfacial chemistry was optimized and subsequently tested in a simulated marine environment at the National Oil Spill Response Research & Renewable Energy Test Facility, Ohmsett. We find favorable performance for surface oil mitigation and, for the first time, demonstrate the advanced sorbent's efficiency and efficacy at pilot scale in extraction of crude oil and refined petroleum products dispersed in the water column. As a result, this is a potentially disruptive technology, opening a new field of environmental science focused on sub-surface pollutant sequestration.
Assembly procedure for column cutting platform
International Nuclear Information System (INIS)
Routh, R.D.
1995-01-01
This supporting document describes the assembly procedure for the Column Cutting Platform and Elevation Support. The Column Cutting Platform is a component of the 241-SY-101 Equipment Removal System. It is set up on the deck of the Strongback Trailer to provide work access to cut off the upper portion of the Mitigation Pump Assembly (MPA). The Elevation Support provides support for the front of the Storage Container with the Strongback at an inclined position. The upper portion of the MPA must be cut off to install the Containment Caps on the Storage Container. The storage Container must be maintained in an inclined position until the Containment Caps are installed to prevent any residual liquids from migrating forward in the Storage Container
Modeling of Crystalline Silicotitanate Ion Exchange Columns
International Nuclear Information System (INIS)
Walker, D.D.
1999-01-01
Non-elutable ion exchange is being considered as a potential replacement for the In-Tank Precipitation process for removing cesium from Savannah River Site (SRS) radioactive waste. Crystalline silicotitanate (CST) particles are the reference ion exchange medium for the process. A major factor in the construction cost of this process is the size of the ion exchange column required to meet product specifications for decontaminated waste. To validate SRS column sizing calculations, SRS subcontracted two reknowned experts in this field to perform similar calculations: Professor R. G. Anthony, Department of Chemical Engineering, Texas A ampersand 038;M University, and Professor S. W. Wang, Department of Chemical Engineering, Purdue University. The appendices of this document contain reports from the two subcontractors. Definition of the design problem came through several meetings and conference calls between the participants and SRS personnel over the past few months. This document summarizes the problem definition and results from the two reports
Optimization of the isotope separation in columns
International Nuclear Information System (INIS)
Kaminskij, V.A.; Vetsko, V.M.; Tevzadze, G.A.; Devdariani, O.A.; Sulaberidze, G.A.
1982-01-01
The general method for the multi-parameter optimization of cascade plants of packed columns is proposed. As an optimization effectiveness function a netcost of the isotopic product is selected. The net cost is comprehensively characterizing the sum total of capital costs for manufacturing the products as well as determining the choice of the most effective directions for capital investments and rational limits of improvement of the products quality. The method is based on main representations of the cascade theory, such as the ideal flow profile and form efficiency as well as mathematical model of the packed column specifying the bonds between its geometric and operating parameters. As a result, the isotopic products cost function could be bound with such parameters as the equilibrium stage height, ultimate packing capacity, its element dimensions, column diameter. It is concluded that the suggested approach to the optimization of isotope separation processes is rather a general one. It permits to solve a number of special problems, such as estimation of advisability of using heat-pump circuits and determining the rational automation level. Besides, by means of the method suggested one can optimize the process conditions with regard to temperature and pressure
Employing anatomical knowledge in vertebral column labeling
Yao, Jianhua; Summers, Ronald M.
2009-02-01
The spinal column constitutes the central axis of human torso and is often used by radiologists to reference the location of organs in the chest and abdomen. However, visually identifying and labeling vertebrae is not trivial and can be timeconsuming. This paper presents an approach to automatically label vertebrae based on two pieces of anatomical knowledge: one vertebra has at most two attached ribs, and ribs are attached only to thoracic vertebrae. The spinal column is first extracted by a hybrid method using the watershed algorithm, directed acyclic graph search and a four-part vertebra model. Then curved reformations in sagittal and coronal directions are computed and aggregated intensity profiles along the spinal cord are analyzed to partition the spinal column into vertebrae. After that, candidates for rib bones are detected using features such as location, orientation, shape, size and density. Then a correspondence matrix is established to match ribs and vertebrae. The last vertebra (from thoracic to lumbar) with attached ribs is identified and labeled as T12. The rest of vertebrae are labeled accordingly. The method was tested on 50 CT scans and successfully labeled 48 of them. The two failed cases were mainly due to rudimentary ribs.
Local buckling of composite channel columns
Szymczak, Czesław; Kujawa, Marcin
2018-05-01
The investigation concerns local buckling of compressed flanges of axially compressed composite channel columns. Cooperation of the member flange and web is taken into account here. The buckling mode of the member flange is defined by rotation angle a flange about the line of its connection with the web. The channel column under investigation is made of unidirectional fibre-reinforced laminate. Two approaches to member orthotropic material modelling are performed: the homogenization with the aid of theory of mixture and periodicity cell or homogenization upon the Voigt-Reuss hypothesis. The fundamental differential equation of local buckling is derived with the aid of the stationary total potential energy principle. The critical buckling stress corresponding to a number of buckling half-waves is assumed to be a minimum eigenvalue of the equation. Some numerical examples dealing with columns are given here. The analytical results are compared with the finite element stability analysis carried out by means of ABAQUS software. The paper is focused on a close analytical solution of the critical buckling stress and the associated buckling mode while the web-flange cooperation is assumed.
Substrate Integrated Evanescent Filters Employing Coaxial Stubs
DEFF Research Database (Denmark)
Zhurbenko, Vitaliy
2015-01-01
Evanescent mode substrate integrated waveguide (SIW) is one of the promising technologies for design of light-weight low-cost microwave components. Traditional realization methods used in the standard evanescent waveguide technology are often not directly applicable to SIW due to dielectric filli...... of the microwave filter are discussed. The approach is useful in applications where a sharp roll-off at the upper stop-band is required....
Helmueller, Shawn C; Poe, Donald P; Kaczmarski, Krzysztof
2018-02-02
An approach to conducting SFC separations under pseudo-adiabatic condition utilizing a dual-zone column heater is described. The heater allows for efficient separations at low pressures above the critical temperature by imposing a temperature profile along the column wall that closely matches that for isenthalpic expansion of the fluid inside the column. As a result, the efficiency loss associated with the formation of radial temperature gradients in this difficult region can be largely avoided in packed analytical scale columns. For elution of n-octadecylbenzene at 60 °C with 5% methanol modifier and a flow rate of 3 mL/min, a 250 × 4.6-mm column packed with 5-micron Kinetex C18 particles began to lose efficiency (8% decrease in the number of theoretical plates) at outlet pressures below 142 bar in a traditional forced air oven. The corresponding outlet pressure for onset of excess efficiency loss was decreased to 121 bar when the column was operated in a commercial HPLC column heater, and to 104 bar in the new dual-zone heater operated in adiabatic mode, with corresponding increases in the retention factor for n-octadecylbenzene from 2.9 to 6.8 and 14, respectively. This approach allows for increased retention and efficient separations of otherwise weakly retained analytes. Applications are described for rapid SFC separation of an alkylbenzene mixture using a pressure ramp, and isobaric separation of a cannabinoid mixture. Copyright © 2018 Elsevier B.V. All rights reserved.
Ductility of reinforced concrete columns confined with stapled strips
International Nuclear Information System (INIS)
Tahir, M.F.; Khan, Q.U.Z.; Shabbir, F.; Sharif, M.B.; Ijaz, N.
2015-01-01
Response of three 150x150x450mm short reinforced concrete (RC) columns confined with different types of confining steel was investigated. Standard stirrups, strips and stapled strips, each having same cross-sectional area, were employed as confining steel around four comer column bars. Experimental work was aimed at probing into the affect of stapled strip confinement on post elastic behavior and ductility level under cyclic axial load. Ductility ratios, strength enhancement factor and core concrete strengths were compared to study the affect of confinement. Results indicate that strength enhancement in RC columns due to strip and stapled strip confinement was not remarkable as compared to stirrup confined column. It was found that as compared to stirrup confined column, stapled strip confinement enhanced the ductility of RC column by 183% and observed axial capacity of stapled strip confined columns was 41 % higher than the strip confined columns. (author)
EX0904 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0904: Water Column Exploration Field...
Cross flow cyclonic flotation column for coal and minerals beneficiation
Lai, Ralph W.; Patton, Robert A.
2000-01-01
An apparatus and process for the separation of coal from pyritic impurities using a modified froth flotation system. The froth flotation column incorporates a helical track about the inner wall of the column in a region intermediate between the top and base of the column. A standard impeller located about the central axis of the column is used to generate a centrifugal force thereby increasing the separation efficiency of coal from the pyritic particles and hydrophillic tailings.
Behaviour of FRP confined concrete in square columns
Diego Villalón, Ana de; Arteaga Iriarte, Ángel; Fernandez Gomez, Jaime Antonio; Perera Velamazán, Ricardo; Cisneros, Daniel
2015-01-01
A significant amount of research has been conducted on FRP-confined circular columns, but much less is known about rectangular/square columns in which the effectiveness of confinement is much reduced. This paper presents the results of experimental investigations on low strength square concrete columns confined with FRP. Axial compression tests were performed on ten intermediate size columns. The tests results indicate that FRP composites can significantly improve the bearing capacity and duc...
Modalization in the Political Column of Tempo Magazine
Rahmah, Maria Betti Sinaga and
2017-01-01
The study focuses on analyzing the use of modalization in the Political Column of Tempo Magazine. The objectives were to find out the type of modalization and to describe the use of modalization in the Political Column of Tempo magazine. The data were taken from Political Column of Tempo magazine published in June and July 2017. The source of data was Political Column in Tempo magazine. The data analysis applied descriptive qualitative research. There were 135 clauses which contained Modaliza...
Numerical Simulations of Settlement of Jet Grouting Columns
Directory of Open Access Journals (Sweden)
Juzwa Anna
2016-03-01
Full Text Available The paper presents the comparison of results of numerical analyses of interaction between group of jet grouting columns and subsoil. The analyses were conducted for single column and groups of three, seven and nine columns. The simulations are based on experimental research in real scale which were carried out by authors. The final goal for the research is an estimation of an influence of interaction between columns working in a group.
column frame for design of reinforced concrete sway frames
African Journals Online (AJOL)
adminstrator
design of slender reinforced concrete columns in sway frames according .... concrete,. Ac = gross cross-sectional area of the columns. Step 3: Effective Buckling Length Factors. The effective buckling length factors of columns in a sway frame shall be computed by .... shall have adequate resistance to failure in a sway mode ...
Behavior of reinforced concrete columns strenghtened by partial jacketing
Directory of Open Access Journals (Sweden)
D. B. FERREIRA
Full Text Available This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column e PR (reference column. The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.
46 CFR 174.085 - Flooding on column stabilized units.
2010-10-01
... 46 Shipping 7 2010-10-01 2010-10-01 false Flooding on column stabilized units. 174.085 Section 174... Units § 174.085 Flooding on column stabilized units. (a) Watertight compartments that are outboard of... of the unit, must be assumed to be subject to flooding as follows: (1) When a column is subdivided...
Water hammer with column separation : a historical review
Bergant, A.; Simpson, A.R.; Tijsseling, A.S.
2006-01-01
Column separation refers to the breaking of liquid columns in fully filled pipelines. This may occur in a water-hammer event when the pressure in a pipeline drops to the vapor pressure at specific locations such as closed ends, high points or knees (changes in pipe slope). The liquid columns are
Hydrodynamic Study Of Column Bioleaching Processes
Directory of Open Access Journals (Sweden)
Sadowski Zygmunt
2015-06-01
Full Text Available The modelling of flow leaching solution through the porous media has been considered. The heap bioleaching process can be tested using the column experimental equipment. This equipment was employed to the hydrodynamic studies of copper ore bioleaching. The copper ore (black shale ore with the support, inertial materials (glass small balls and polyethylene beads was used to the bioleaching tests. The packed beds were various composition, the ore/support ratio was changed. The correlation between the bed porosity and bioleaching kinetics, and copper recovery was investigated.
Column leaching from biomass combustion ashes
DEFF Research Database (Denmark)
Maresca, Alberto; Astrup, Thomas Fruergaard
2015-01-01
The utilization of biomass combustion ashes for forest soil liming and fertilizing has been addressed in literature. Though, a deep understanding of the ash chemical composition and leaching behavior is necessary to predict potential benefits and environmental risks related to this practice....... In this study, a fly ash sample from an operating Danish power plant based on wood biomass was collected, chemically characterized and investigated for its leaching release of nutrients and heavy metals. A column leaching test was employed. The strongly alkaline pH of all the collected eluates suggested...
Design of Steel Beam-Column Connections
Directory of Open Access Journals (Sweden)
Bogatinoski Z.
2014-05-01
Full Text Available In this paper a theoretical and experimental research of the steel beam-column connections is presented. Eight types of specimens were being researched, composed of rigid and semi-rigid connections from which 4 connections are with IPE - profile and 4 connections with tube's section for the beam. From the numerical analysis of the researched models, and especially from the experimental research at the Laboratory for Structures in the Faculty of Mechanical Engineering - Skopje, specific conclusions were received that ought to have theoretical and practical usage for researchers in this area of interest.
Buckling driven debonding in sandwich columns
DEFF Research Database (Denmark)
Østergaard, Rasmus Christian
2008-01-01
results from two mechanisms: (a) interaction of local debond buckling and global buckling and (b) the development of a damaged zone at the debond crack tip. Based on the pronounced imperfection sensitivity, the author predicts that an experimental measurement of the strength of sandwich structures may......A compression loaded sandwich column that contains a debond is analyzed using a geometrically non-linear finite element model. The model includes a cohesive zone along one face sheet/core interface whereby the debond can extend by interface crack growth. Two geometrical imperfections are introduced...
Dynamic Deformation and Collapse of Granular Columns
Uenishi, K.; Tsuji, K.; Doi, S.
2009-12-01
Large dynamic deformation of granular materials may be found in nature not only in the failure of slopes and cliffs — due to earthquakes, rock avalanches, debris flows and landslides — but also in earthquake faulting itself. Granular surface flows often consist of solid grains and intergranular fluid, but the effect of the fluid may be usually negligible because the volumetric concentration of grains is in many cases high enough for interparticle forces to dominate momentum transport. Therefore, the investigation of dry granular flow of a mass might assist in further understanding of the above mentioned geophysical events. Here, utilizing a high-speed digital video camera system, we perform a simple yet fully-controlled series of laboratory experiments related to the collapse of granular columns. We record, at an interval of some microseconds, the dynamic transient granular mass flow initiated by abrupt release of a tube that contains dry granular materials. The acrylic tube is partially filled with glass beads and has a cross-section of either a fully- or semi-cylindrical shape. Upon sudden removal of the tube, the granular solid may fragment under the action of its own weight and the particles spread on a rigid horizontal plane. This study is essentially the extension of the previous ones by Lajeunesse et al. (Phys. Fluids 2004) and Uenishi and Tsuji (JPGU 2008), but the striped layers of particles in a semi-cylindrical tube, newly introduced in this contribution, allow us to observe the precise particle movement inside the granular column: The development of slip lines inside the column and the movement of particles against each other can be clearly identified. The major controlling parameters of the spreading dynamics are the initial aspect ratio of the granular (semi-)cylindrical column, the frictional properties of the horizontal plane (substrate) and the size of beads. We show the influence of each parameter on the average flow velocity and final radius
A review of oscillating water columns.
Heath, T V
2012-01-28
This paper considers the history of oscillating water column (OWC) systems from whistling buoys to grid-connected power generation systems. The power conversion from the wave resource through to electricity via pneumatic and shaft power is discussed in general terms and with specific reference to Voith Hydro Wavegen's land installed marine energy transformer (LIMPET) plant on the Scottish island of Islay and OWC breakwater systems. A report on the progress of other OWC systems and power take-off units under commercial development is given, and the particular challenges faced by OWC developers reviewed.
Preinjector for Linac 1, accelerating column
1974-01-01
For a description of the Linac 1 preinjector, please see first 7403070X. High up on the wall of the Faraday cage (7403073X) is this drum-shaped container of the ion source (7403083X). It is mounted at the HV end of the accelerating column through which the ions (usually protons; many other types of ions in the course of its long history) proceed through the Faraday cage wall to the low-energy end (at ground potential) of Linac 1. The 520 kV accelerating voltage was supplied by a SAMES generator (7403074X).
Column studies on BTEX biodegradation under microaerophilic and denitrifying conditions
International Nuclear Information System (INIS)
Hutchins, S.R.; Moolenaar, S.W.; Rhodes, D.E.
1992-01-01
Two column tests were conducted using aquifer material to simulate the nitrate field demonstration project carried out earlier at Traverse City, Michigan. The objectives were to better define the effect nitrate addition had on biodegradation of benzene, toluene, ethylbenzene, xylenes, and trimethylbenzenes (BTEX) in the field study, and to determine whether BTEX removal can be enhanced by supplying a limited amount of oxygen as a supplemental electron acceptor. Columns were operated using limited oxygen, limited oxygen plus nitrate, and nitrate alone. In the first column study, benzene was generally recalcitrant compared to the alkylbenzenes (TEX), although some removal did occur. In the second column study, nitrate was deleted from the feed to the column originally receiving nitrate alone and added to the feed of the column originally receiving limited oxygen alone. Although the requirement for nitrate for optimum TEX removal was clearly demonstrated in these columns, there were significant contributions by biotic and abiotic processes other than denitrification which could not be quantified
Spinal column damage from water ski jumping
International Nuclear Information System (INIS)
Horne, J.; Cockshott, W.P.; Shannon, H.S.
1987-01-01
We conducted a radiographic survey of 117 competitive water ski jumpers to determine whether this sport can cause spinal column damage and, if so, whether damage is more likely to occur in those who participate during the period of spinal growth and development (age 15 years or younger). We found a high prevalence of two types of abnormality: Scheuermann (adolescent) spondylodystrophy (present in 26% of the skiers) and vertebral body wedging (present in 34%). The prevalence of adolescent spondylodystrophy increased with the number of years of participation in the sport before age 15 years or less. Of those in this age group who had skied for 5 years or more, 57 showed adolescent spondylodystrophy; of those in the same age group who had skied for 9 years or more, 100% were affected. Wedged vertebrae increased as time of participation increased, regardless of the age at which exposure began. We conclude that competitive water ski jumping may damage the spinal column and that consideration should be given to regulating this sport, particularly for children. (orig.)
Spinal column damage from water ski jumping.
Horne, J; Cockshott, W P; Shannon, H S
1987-01-01
We conducted a radiographic survey of 117 competitive water ski jumpers to determine whether this sport can cause spinal column damage and, if so, whether damage is more likely to occur in those who participate during the period of spinal growth and development (age 15 years or younger). We found a high prevalence of two types of abnormality: Scheuermann (adolescent) spondylodystrophy (present in 26% of the skiers) and vertebral body wedging (present in 34%). The prevalence of adolescent spondylodystrophy increased with the number of years of participation in the sport before age 15 years or less. Of those in this age group who had skied for 5 years or more, 57 showed adolescent spondylodystrophy; of those in the same age group who had skied for 9 years or more, 100% were affected. Wedged vertebrae increased as time of participation increased, regardless of the age at which exposure began. We conclude that competitive water ski jumping may damage the spinal column and that consideration should be given to regulating this sport, particularly for children.
Picobubble column flotation of fine coal
Energy Technology Data Exchange (ETDEWEB)
Daniel Tao; Samuel Yu; Xiaohua Zhou; R.Q. Honaker; B.K. Parekh [University of Kentucky, Lexington, KY (United States). Department of Mining Engineering
2008-01-15
Froth flotation is widely used in the coal industry to clean -28 mesh (0.6 mm) or -100 mesh (0.15 mm) fine coal. A successful recovery of particles by flotation depends on efficient particle-bubble collision and attachment with minimal subsequent particle detachment from bubble. Flotation is effective in a narrow size range, nominally 10-100 {mu}m, beyond which the flotation efficiency drops sharply. A fundamental analysis has shown that use of picobubbles can significantly improve the flotation recovery of particles by increasing the probability of collision and attachment and reducing the probability of detachment. A specially designed column with a picobubble generator has been developed for enhanced recovery of fine coal particles. Picobubbles were produced based on the hydrodynamic cavitation principle. Experimental results have shown that the use of picobubbles in a 5-cm diameter column flotation increased the combustible recovery of a highly floatable coal by up to 10% and that of a poorly floatable coal by up to 40%, depending on the feed rate, collector dosage, and other flotation conditions. 14 refs.
Spinal column damage from water ski jumping
Energy Technology Data Exchange (ETDEWEB)
Horne, J.; Cockshott, W.P.; Shannon, H.S.
1987-11-01
We conducted a radiographic survey of 117 competitive water ski jumpers to determine whether this sport can cause spinal column damage and, if so, whether damage is more likely to occur in those who participate during the period of spinal growth and development (age 15 years or younger). We found a high prevalence of two types of abnormality: Scheuermann (adolescent) spondylodystrophy (present in 26% of the skiers) and vertebral body wedging (present in 34%). The prevalence of adolescent spondylodystrophy increased with the number of years of participation in the sport before age 15 years or less. Of those in this age group who had skied for 5 years or more, 57 showed adolescent spondylodystrophy; of those in the same age group who had skied for 9 years or more, 100% were affected. Wedged vertebrae increased as time of participation increased, regardless of the age at which exposure began. We conclude that competitive water ski jumping may damage the spinal column and that consideration should be given to regulating this sport, particularly for children. (orig.)
Hydrogen isotope exchange in metal hydride columns
International Nuclear Information System (INIS)
Wiswall, R.; Reilly, J.; Bloch, F.; Wirsing, E.
1977-01-01
Several metal hydrides were shown to act as chromatographic media for hydrogen isotopes. The procedure was to equilibrate a column of hydride with flowing hydrogen, inject a small quantity of tritium tracer, and observe its elution behavior. Characteristic retention times were found. From these and the extent of widening of the tritium band, the heights equivalent to a theoretical plate could be calculated. Values of around 1 cm were obtained. The following are the metals whose hydrides were studied, together with the temperature ranges in which chromatographic behavior was observed: vanadium, 0 to 70 0 C; zirconium, 500 to 600 0 C; LaNi 5 , -78 to +30 0 C; Mg 2 Ni, 300 to 375 0 C; palladium, 0 to 70 0 C. A dual-temperature isotope separation process based on hydride chromatography was demonstrated. In this, a column was caused to cycle between two temperatures while being supplied with a constant stream of tritium-traced hydrogen. Each half-cycle was continued until ''breakthrough,'' i.e., until the tritium concentration in the effluent was the same as that in the feed. Up to that point, the effluent was enriched or depleted in tritium, by up to 20%
Improved focusing-and-deflection columns
International Nuclear Information System (INIS)
Mui, P.H.; Szilagyi, M.
1995-01-01
Our earlier design procedures for constructing quadrupole columns are further expanded to include octupole corrector units and ''octupole'' deflectors with no third-order harmonics. The additional complications are finer partitioning of the plates and increased number of voltage controllers. Two sample designs, one having only the additional octupole deflectors and one having both the deflectors and the correctors, are presented and compared to our previous quadrupole system. The additional octupole components are shown to be capable of increasing the current density from 30% to more than 300% for a four-plate system, designed to focus and scan the electron beam over a circular area of 0.25 mm radius. The electron beam is assumed to have an initial divergence of ±2.3 mrad, an initial energy of 6 kV, a total energy spread of 1 eV, and a final acceleration of 30 keV. These systems are then slightly reoptimized for a superficial comparison with the commercially available column by Micrion Corporation. The numerical results indicate a potential for substantial improvements, demonstrating the power of this design procedure. Finally, a discussion is presented on how the individual components can interact with each other to reduce the various aberrations. copyright 1995 American Vacuum Society
Synthesis of focusing-and-deflection columns
International Nuclear Information System (INIS)
Szilagyi, M.; Mui, P.H.
1995-01-01
Szilagyi and Szep have demonstrated that focusing lenses of high performances can be constructed from a column of circular plate electrodes. Later, Szilagyi modified that system to include dipole, quadrupole, and octupole components by partitioning each plate into eight equal sectors. It has already been shown that the additional quadrupole components can indeed bring about substantial improvements in the focusing of charged particle beams. In this article, that design procedure is expanded to construct columns capable of both focusing and deflecting particle beams by just introducing additional dipole components. In this new design, the geometry of the system remains unchanged. The only extra complication is the demand for more individual controls of the sector voltages. Two sample designs, one for negative ions and one for electrons, are presented showing that in both cases a ±2.3 mrad diverging beam can be focused down to a spot of less than 50 nm in radius over a scanning circular area of radius 0.25 mm. The details of the two systems are given in Sec. IV along with the source conditions. The performance of the negative ion system is found to be comparable to the published data. For the relativistic electron system, the interaction of individual components to reduce various aberrations is investigated. copyright 1995 American Vacuum Society
Muamar Rifa'i, Alfian; Setiawan, Bambang; Djarwanti, Noegroho
2017-12-01
The expansive soil is soil that has a potential for swelling-shrinking due to changes in water content. Such behavior can exert enough force on building above to cause damage. The use of columns filled with additives such as Calcium Carbide is done to reduce the negative impact of expansive soil behavior. This study aims to determine the effect of carbide columns on expansive soil. Observations were made on swelling and spreading of carbides in the soil. 7 Carbide columns with 5 cm diameter and 20 cm height were installed into the soil with an inter-column spacing of 8.75 cm. Wetting is done through a pipe at the center of the carbide column for 20 days. Observations were conducted on expansive soil without carbide columns and expansive soil with carbide columns. The results showed that the addition of carbide column could reduce the percentage of swelling by 4.42%. Wetting through the center of the carbide column can help spread the carbide into the soil. The use of carbide columns can also decrease the rate of soil expansivity. After the addition of carbide column, the plasticity index value decreased from 71.76% to 4.3% and the shrinkage index decreased from 95.72% to 9.2%.
Heat Transfer Analysis for a Fixed CST Column
International Nuclear Information System (INIS)
Lee, S.Y.
2004-01-01
In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow condition through the column was assumed as one of the reference conditions for the simulation of a loss-of-flow accident. A series of the modeling calculations has been performed using a computational heat transfer approach. Results for the baseline model indicate that transit times to reach 130 degrees Celsius maximum temperature of the CST-salt solution column are about 96 hours when the 20-in CST column with 300 Ci/liter heat generation source and 25 degrees Celsius initial column temperature is cooled by natural convection of external air as a primary heat transfer mechanism. The modeling results for the 28-in column equipped with water jacket systems on the external wall surface of the column and water coolant pipe at the center of the CST column demonstrate that the column loaded with 300 Ci/liter heat source can be maintained non-boiling indefinitely. Sensitivity calculations for several alternate column sizes, heat loads of the packed column, engineered cooling systems, and various ambient conditions at the exterior wall of the column have been performed under the reference conditions of the CST-salt solution to assess the impact of those parameters on the peak temperatures of the packed column for a given transient time. The results indicate that a water-coolant pipe at the center of the CST column filled with salt solution is the most effective one among the potential design parameters related to the thermal energy dissipation of decay heat load. It is noted that the cooling mechanism at the wall boundary of the column has significant
Gupta, Vipul; Beirne, Stephen; Nesterenko, Pavel N; Paull, Brett
2018-01-16
Effect of column geometry on the liquid chromatographic separations using 3D printed liquid chromatographic columns with in-column polymerized monoliths has been studied. Three different liquid chromatographic columns were designed and 3D printed in titanium as 2D serpentine, 3D spiral, and 3D serpentine columns, of equal length and i.d. Successful in-column thermal polymerization of mechanically stable poly(BuMA-co-EDMA) monoliths was achieved within each design without any significant structural differences between phases. Van Deemter plots indicated higher efficiencies for the 3D serpentine chromatographic columns with higher aspect ratio turns at higher linear velocities and smaller analysis times as compared to their counterpart columns with lower aspect ratio turns. Computational fluid dynamic simulations of a basic monolithic structure indicated 44%, 90%, 100%, and 118% higher flow through narrow channels in the curved monolithic configuration as compared to the straight monolithic configuration at linear velocities of 1, 2.5, 5, and 10 mm s -1 , respectively. Isocratic RPLC separations with the 3D serpentine column resulted in an average 23% and 245% (8 solutes) increase in the number of theoretical plates as compared to the 3D spiral and 2D serpentine columns, respectively. Gradient RPLC separations with the 3D serpentine column resulted in an average 15% and 82% (8 solutes) increase in the peak capacity as compared to the 3D spiral and 2D serpentine columns, respectively. Use of the 3D serpentine column at a higher flow rate, as compared to the 3D spiral column, provided a 58% reduction in the analysis time and 74% increase in the peak capacity for the isocratic separations of the small molecules and the gradient separations of proteins, respectively.
Column properties and flow profiles of a flat, wide column for high-pressure liquid chromatography.
Mriziq, Khaled S; Guiochon, Georges
2008-04-11
The design and the construction of a pressurized, flat, wide column for high-performance liquid chromatography (HPLC) are described. This apparatus, which is derived from instruments that implement over-pressured thin layer chromatography, can carry out only uni-dimensional chromatographic separations. However, it is intended to be the first step in the development of more powerful instruments that will be able to carry out two-dimensional chromatographic separations, in which case, the first separation would be a space-based separation, LC(x), taking place along one side of the bed and the second separation would be a time-based separation, LC(t), as in classical HPLC but proceeding along the flat column, not along a tube. The apparatus described consists of a pressurization chamber made of a Plexiglas block and a column chamber made of stainless steel. These two chambers are separated by a thin Mylar membrane. The column chamber is a cavity which is filled with a thick layer (ca. 1mm) of the stationary phase. Suitable solvent inlet and outlet ports are located on two opposite sides of the sorbent layer. The design allows the preparation of a homogenous sorbent layer suitable to be used as a chromatographic column, the achievement of effective seals of the stationary phase layer against the chamber edges, and the homogenous flow of the mobile phase along the chamber. The entire width of the sorbent layer area can be used to develop separations or elute samples. The reproducible performance of the apparatus is demonstrated by the chromatographic separations of different dyes. This instrument is essentially designed for testing detector arrays to be used in a two-dimensional LC(x) x LC(t) instrument. The further development of two-dimension separation chromatographs based on the apparatus described is sketched.
Strengthening of Steel Columns under Load: Torsional-Flexural Buckling
Directory of Open Access Journals (Sweden)
Martin Vild
2016-01-01
Full Text Available The paper presents experimental and numerical research into the strengthening of steel columns under load using welded plates. So far, the experimental research in this field has been limited mostly to flexural buckling of columns and the preload had low effect on the column load resistance. This paper focuses on the local buckling and torsional-flexural buckling of columns. Three sets of three columns each were tested. Two sets corresponding to the base section (D and strengthened section (E were tested without preloading and were used for comparison. Columns from set (F were first preloaded to the load corresponding to the half of the load resistance of the base section (D. Then the columns were strengthened and after they cooled, they were loaded to failure. The columns strengthened under load (F had similar average resistance as the columns welded without preloading (E, meaning the preload affects even members susceptible to local buckling and torsional-flexural buckling only slightly. This is the same behaviour as of the tested columns from previous research into flexural buckling. The study includes results gained from finite element models of the problem created in ANSYS software. The results obtained from the experiments and numerical simulations were compared.
Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns
International Nuclear Information System (INIS)
Clark, E.A.
1992-01-01
Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (AHL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of cracking was observed in the AHL block TCAP in a location expected to experience the highest thermal shock fatigue in this design. It is important to limit thermal stresses caused by constraint in hydride systems designed to work by temperature variation, such as hydride storage beds and TCAP columns
Refreshment topics II: Design of distillation columns
Directory of Open Access Journals (Sweden)
Milojević Svetomir
2006-01-01
Full Text Available For distillation column design it is necessary to define all the variable parameters such as component concentrations in different streams temperatures, pressures, mass and energy flow, which are used to represent the separation process of some specific system. They are related to each other according to specific laws, and if the number of such parameters exceeds the number of their relationships, in order to solve a problem some of them must be specified in advance or some constraints assumed for the mass balance, the balance of energy, phase equilibria or chemical equilibria. Knowledge of specific elements which are the constituents of a distillation unit must be known to define the number of design parameters as well as some additional apparati also necessary to realize the distilation. Each separate apparatus might be designed and constructed only if all the necessary and variable parameters for such a unit are defined. This is the right route to solve a distilation unit in many different cases. The construction of some distillation unit requires very good knowledge of mass, heat and momentum transfer phenomena. Moreover, the designer needs to know which kind of apparatus will be used in the distillation unit to realize a specific production process. The most complicated apparatus in a rectification unit is the distillation column. Depending on the complexity of the separation process one, two or more columns are often used. Additional equipment are heat exchangers (reboilers, condensers, cooling systems, heaters, separators, tanks for reflux distribution, tanks and pumps for feed transportation, etc. Such equipment is connected by pipes and valves, and for the normal operation of a distillation unit other instruments for measuring the flow rate, temperature and pressure are also required. Problems which might arise during the determination and selection of such apparati and their number requires knowledge of the specific systems which must
Retention of nitrous gases in scrubber columns
International Nuclear Information System (INIS)
Nakazone, A.K.; Costa, R.C.; Lobao, A.S.T.; Matsuda, H.T.; Araujo, B.F. de
1988-01-01
During the UO 2 dissolution in nitric acid, some different species of NO (sub)x are released. The off gas can either be refluxed to the dissolver or be released and retained on special colums. The final composition of the solution is the main parameter to take in account. A process for nitrous gases retention using scrubber colums containing H 2 O or diluted HNO 3 is presented. Chemiluminescence measurement was employed to NO x evaluation before and after scrubing. Gas flow, temperature, residence time are the main parameters considered in this paper. For the dissolution of 100g UO 2 in 8M nitric acid, a 6NL/h O 2 flow was the best condition for the NO/NO 2 oxidation with maximum absorption in the scrubber columns. (author) [pt
Education and training column: the learning collaborative.
MacDonald-Wilson, Kim L; Nemec, Patricia B
2015-03-01
This column describes the key components of a learning collaborative, with examples from the experience of 1 organization. A learning collaborative is a method for management, learning, and improvement of products or processes, and is a useful approach to implementation of a new service design or approach. This description draws from published material on learning collaboratives and the authors' experiences. The learning collaborative approach offers an effective method to improve service provider skills, provide support, and structure environments to result in lasting change for people using behavioral health services. This approach is consistent with psychiatric rehabilitation principles and practices, and serves to increase the overall capacity of the mental health system by structuring a process for discovering and sharing knowledge and expertise across provider agencies. (PsycINFO Database Record (c) 2015 APA, all rights reserved).
[Lateral column lengthening osteotomy of calcaneus].
Hintermann, B
2015-08-01
Lengthening of the lateral column for adduction of forefoot and restoration of the medial arch. Stabilization of the ankle joint complex. Supple flatfoot deformity (posterior tibial tendon dysfunction stage II). Instability of the medial ankle joint complex (superficial deltoid and spring ligament). Posttraumatic valgus and pronation deformity of the foot. Rigid flatfoot deformity (posterior tibial tendon dysfunction stage III and IV). Talocalcaneal and naviculocalcaneal coalition. Osteoarthritis of calcaneocuboid joint. Exposition of calcaneus at sinus tarsi. Osteotomy through sinus tarsi and widening until desired correction of the foot is achieved. Insertion of bone graft. Screw fixation. Immobilization in a cast for 6 weeks. Weight-bearing as tolerated from the beginning. In the majority of cases, part of hindfoot reconstruction. Reliable and stable correction. Safe procedure with few complications.
Yield stress independent column buckling curves
DEFF Research Database (Denmark)
Stan, Tudor‐Cristian; Jönsson, Jeppe
2017-01-01
of the yield stress is to some inadequate degree taken into account in the Eurocode by specifying that steel grades of S460 and higher all belong to a common set of “raised” buckling curves. This is not satisfying as it can be shown theoretically that the current Eurocode formulation misses an epsilon factor......Using GMNIA and shell finite element modelling of steel columns it is ascertained that the buckling curves for given imperfections and residual stresses are not only dependent on the relative slenderness ratio and the cross section shape but also on the magnitude of the yield stress. The influence...... in the definition of the normalised imperfection magnitudes. By introducing this factor it seems that the GMNIA analysis and knowledge of the independency of residual stress levels on the yield stress can be brought together and give results showing consistency between numerical modelling and a simple modified...
Calculation of a TBP extraction column
International Nuclear Information System (INIS)
Lima Soares, M.L. de.
1973-01-01
Problems involving the number of stages in an extraction column and the equipment needed in most aqueous methods of reprocessing of nuclear fuels were studied. A solution for the separation of uranium from fission products in a feed solution that contains these components plus nitric acid, thorium and protactinium is obtained. The program has peculiarities such as treatment of tracer components; acceptance of decontamination and recuperation factors better than the set values for the solution; occurrence of niaxima concentrations; change of key component; criterion for ending of section; corrections for interaction; input data not including concentration estimates of the raffinate and organic extract; set of limitations for the concentrations based on input data to help convergence
Experimental validation of pulsed column inventory estimators
International Nuclear Information System (INIS)
Beyerlein, A.L.; Geldard, J.F.; Weh, R.; Eiben, K.; Dander, T.; Hakkila, E.A.
1991-01-01
Near-real-time accounting (NRTA) for reprocessing plants relies on the timely measurement of all transfers through the process area and all inventory in the process. It is difficult to measure the inventory of the solvent contractors; therefore, estimation techniques are considered. We have used experimental data obtained at the TEKO facility in Karlsruhe and have applied computer codes developed at Clemson University to analyze this data. For uranium extraction, the computer predictions agree to within 15% of the measured inventories. We believe this study is significant in demonstrating that using theoretical models with a minimum amount of process data may be an acceptable approach to column inventory estimation for NRTA. 15 refs., 7 figs
Energy Technology Data Exchange (ETDEWEB)
Hegedűs, Árpád; Konczer, József [MTA Lendület Holographic QFT Group, Wigner Research Centre,H-1525 Budapest 114, P.O.B. 49 (Hungary)
2016-08-09
In this paper, we solved numerically the Quantum Spectral Curve (QSC) equations corresponding to some twist-2 single trace operators with even spin from the sl(2) sector of AdS{sub 5}/CFT{sub 4} correspondence. We describe all technical details of the numerical method which are necessary to implement it in C++ language. In the S=2,4,6,8 cases, our numerical results confirm the analytical results, known in the literature for the first 4 coefficients of the strong coupling expansion for the anomalous dimensions of twist-2 operators. In the case of the Konishi operator, due to the high precision of the numerical data we could give numerical predictions to the values of two further coefficients, as well. The strong coupling behaviour of the coefficients c{sub a,n} in the power series representation of the P {sub a}-functions is also investigated. Based on our numerical data, in the regime, where the index of the coefficients is much smaller than λ{sup 1/4}, we conjecture that the coefficients have polynomial index dependence at strong coupling. This allows one to propose a strong coupling series representation for the P-functions being valid far enough from the real short cut. In the paper the qualitative strong coupling behaviour of the P-functions at the branch points is also discussed.
Novel field emission SEM column with beam deceleration technology
Energy Technology Data Exchange (ETDEWEB)
Jiruše, Jaroslav; Havelka, Miloslav; Lopour, Filip
2014-11-15
A novel field-emission SEM column has been developed that features Beam Deceleration Mode, high-probe current and ultra-fast scanning. New detection system in the column is introduced to detect true secondary electron signal. The resolution power at low energy was doubled for conventional SEM optics and moderately improved for immersion optics. Application examples at low landing energies include change of contrast, imaging of non-conductive samples and thin layers. - Highlights: • A novel field-emission SEM column has been developed. • Implemented beam deceleration improves the SEM resolution at 1 keV two times. • New column maintains high analytical potential and wide field of view. • Detectors integrated in the column allow gaining true SE and BE signal separately. • Performance of the column is demonstrated on low energy applications.
Novel field emission SEM column with beam deceleration technology
International Nuclear Information System (INIS)
Jiruše, Jaroslav; Havelka, Miloslav; Lopour, Filip
2014-01-01
A novel field-emission SEM column has been developed that features Beam Deceleration Mode, high-probe current and ultra-fast scanning. New detection system in the column is introduced to detect true secondary electron signal. The resolution power at low energy was doubled for conventional SEM optics and moderately improved for immersion optics. Application examples at low landing energies include change of contrast, imaging of non-conductive samples and thin layers. - Highlights: • A novel field-emission SEM column has been developed. • Implemented beam deceleration improves the SEM resolution at 1 keV two times. • New column maintains high analytical potential and wide field of view. • Detectors integrated in the column allow gaining true SE and BE signal separately. • Performance of the column is demonstrated on low energy applications
Circular Raft Footings Strengthened by Stone Columns under Static Loads
R. Ziaie Moayed; B. Mohammadi-Haji
2016-01-01
Stone columns have been widely employed to improve the load-settlement characteristics of soft soils. The results of two small scale displacement control loading tests on stone columns were used in order to validate numerical finite element simulations. Additionally, a series of numerical calculations of static loading have been performed on strengthened raft footing to investigate the effects of using stone columns on bearing capacity of footings. The bearing capacity of single and group of ...
Estimation of bearing capacity of floating group of stone columns
Fattah, Mohammed Y.; Al-Neami, Mohammed A.; Shamel Al-Suhaily, Ahmed
2017-01-01
Stone column is one of the ground improvement techniques. This technique has a proven performance, short time schedule, durability, constructability and low costs. The stone column technique has been used as a method of reinforcement of soft ground over the past 30 years. The bearing capacity of the stone column still has high level of uncertainties because the existing formulas for the estimation of the bearing capacity are general and do not take into consideration the type of the stone col...
Uncertain Buckling Load and Reliability of Columns with Uncertain Properties
DEFF Research Database (Denmark)
Köylüoglu, H. U.; Nielsen, Søren R. K.; Cakmak, A. S.
Continuous and finite element methods are utilized to determine the buckling load of columns with material and geometrical uncertainties considering deterministic, stochastic and interval models for the bending rigidity of columns. When the bending rigidity field is assumed to be deterministic, t....... for structural design, the lower bound is of crucial interest. The buckling load of fixed-free, simple-supported, pinned-fixed, fixed-fixed columns and a sample frame are calculated....
The design of a new concept chromatography column.
Camenzuli, Michelle; Ritchie, Harald J; Ladine, James R; Shalliker, R Andrew
2011-12-21
Active Flow Management is a new separation technique whereby the flow of mobile phase and the injection of sample are introduced to the column in a manner that allows migration according to the principles of the infinite diameter column. A segmented flow outlet fitting allows for the separation of solvent or solute that elutes along the central radial section of the column from that of the sample or solvent that elutes along the wall region of the column. Separation efficiency on the analytical scale is increased by 25% with an increase in sensitivity by as much as 52% compared to conventional separations.
Simulation of startup period of hydrogen isotope separation distillation column
International Nuclear Information System (INIS)
Sazonov, A.B.; Kagramanov, Z.G.; Magomedbekov, Eh.P.
2003-01-01
Kinetic procedure for the mathematical simulation of start-up regime of rectification columns for molecular hydrogen isotope separation was developed. Nonstationary state (start-up period) of separating column for rectification of multi-component mixture was calculated. Full information on equilibrium and kinetic physicochemical properties of components in separating mixtures was used for the calculations. Profile of concentration of components by height of column in task moment of time was calculated by means of differential equilibriums of nonstationary mass transfer. Calculated results of nonstationary state of column by the 2 m height, 30 mm diameter during separation of the mixture: 5 % protium, 70 % deuterium, 25 % tritium were illustrated [ru
Response of steel box columns in fire conditions
Directory of Open Access Journals (Sweden)
Mahmood Yahyai
2017-05-01
Full Text Available Effect of elevated temperatures on the mechanical properties of steel, brings the importance of investigating the effect of fire on the steel structures anxiously. Columns, as the main load-carrying part of a structure, can be highly vulnerable to the fire. In this study, the behavior of steel gravity columns with box cross section exposed to fire has been investigated. These kinds of columns are widely used in common steel structures design in Iran. In current study, the behavior of such columns in fire conditions is investigated through the finite element method. To perform this, the finite element model of a steel column which has been previously tested under fire condition, was prepared. Experimental loading and boundary conditions were considered in the model and was analyzed. Results were validated by experimental data and various specimens of gravity box columns were designed according to the Iran’s steel buildings code, and modeled and analyzed using Abaqus software. The effect of width to thickness ratio of column plates, the load ratio and slenderness on the ultimate strength of the column was investigated, and the endurance time was estimated under ISO 834 standard fire curve. The results revealed that an increase in width to thickness ratio and load ratio leads to reduction of endurance time and the effect of width to thickness ratio on the ultimate strength of the column decreases with temperature increase.
Applicability of hydroxylamine nitrate reductant in pulse-column contactors
International Nuclear Information System (INIS)
Reif, D.J.
1983-05-01
Uranium and plutonium separations were made from simulated breeder reactor spent fuel dissolver solution with laboratory-sized pulse column contactors. Hydroxylamine nitrate (HAN) was used for reduction of plutonium (1V). An integrated extraction-partition system, simulating a breeder fuel reprocessing flowsheet, carried out a partial partition of uranium and plutonium in the second contactor. Tests have shown that acceptable coprocessing can be ontained using HAN as a plutonium reductant. Pulse column performance was stable even though gaseous HAN oxidation products were present in the column. Gas evolution rates up to 0.27 cfm/ft 2 of column cross section were tested and found acceptable
Evaluation of Controller Tuning Methods Applied to Distillation Column Control
DEFF Research Database (Denmark)
Nielsen, Kim; W. Andersen, Henrik; Kümmel, Professor Mogens
A frequency domain approach is used to compare the nominal performance and robustness of dual composition distillation column control tuned according to Ziegler-Nichols (ZN) and Biggest Log Modulus Tuning (BLT) for three binary distillation columns, WOBE, LUVI and TOFA. The scope of this is to ex......A frequency domain approach is used to compare the nominal performance and robustness of dual composition distillation column control tuned according to Ziegler-Nichols (ZN) and Biggest Log Modulus Tuning (BLT) for three binary distillation columns, WOBE, LUVI and TOFA. The scope...
Performance of zeolite scavenge column in Xe monitoring system
International Nuclear Information System (INIS)
Wang Qian; Wang Hongxia; Li Wei; Bian Zhishang
2010-01-01
In order to improve the performance of zeolite scavenge column, its ability of removal of humidity and carbon dioxide was studied by both static and dynamic approaches. The experimental results show that various factors, including the column length and diameter, the mass of zeolite, the content of water in air, the temperature rise during adsorption, and the activation effectiveness all effect the performance of zeolite column in scavenging humanity and carbon dioxide. Based on these results and previous experience, an optimized design of the zeolite column is made for use in xenon monitoring system. (authors)
Partial strengthening of R.C square columns using CFRP
Directory of Open Access Journals (Sweden)
Ahmed Shaban Abdel-Hay
2014-12-01
An experimental program was undertaken testing ten square columns 200 × 200 × 2000 mm. One of them was a control specimen and the other nine specimens were strengthened with CFRP. The main parameters studied in this research were the compressive strength of the upper part, the height of the upper poor concrete part, and the height of CFRP wrapped part of column. The experimental results including mode of failure, ultimate load, concrete strain, and fiber strains were analyzed. The main conclusion of this research was, partial strengthening of square column using CFRP can be permitted and gives good results of the column carrying capacity.
Mini-columns for Conducting Breakthrough Experiments. Design and Construction
Energy Technology Data Exchange (ETDEWEB)
Dittrich, Timothy M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Reimus, Paul William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ware, Stuart Douglas [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2015-06-11
Experiments with moderately and strongly sorbing radionuclides (i.e., U, Cs, Am) have shown that sorption between experimental solutions and traditional column materials must be accounted for to accurately determine stationary phase or porous media sorption properties (i.e., sorption site density, sorption site reaction rate coefficients, and partition coefficients or K_{d }values). This report details the materials and construction of mini-columns for use in breakthrough columns to allow for accurate measurement and modeling of sorption parameters. Material selection, construction techniques, wet packing of columns, tubing connections, and lessons learned are addressed.
Comparison and Analysis of Steel Frame Based on High Strength Column and Normal Strength Column
Liu, Taiyu; An, Yuwei
2018-01-01
The anti-seismic performance of high strength steel has restricted its industrialization in civil buildings. In order to study the influence of high strength steel column on frame structure, three models are designed through MIDAS/GEN finite element software. By comparing the seismic performance and economic performance of the three models, the three different structures are comprehensively evaluated to provide some references for the development of high strength steel in steel structure.
Xu, R; Huang, X; Kramer, K J; Hawley, M D
1995-10-10
The chromatographic behavior of quinones derived from the oxidation of dopamine and N-acetyldopamine has been studied using liquid chromatography (LC) with both a diode array detector and an electrochemical detector that has parallel dual working electrodes. When stainless steel columns are used, an anodic peak for the oxidation of the catecholamine is observed at the same retention time as a cathodic peak for the reduction of the catecholamine quinone. In addition, the anodic peak exhibits a tail that extends to a second anodic peak for the catecholamine. The latter peak occurs at the normal retention time of the catecholamine. The origin of this phenomenon has been studied and metallic iron in the stainless steel components of the LC system has been found to reduce the quinones to their corresponding catecholamines. The simultaneous appearance of a cathodic peak for the reduction of catecholamine quinone and an anodic peak for the oxidation of the corresponding catecholamine occurs when metallic iron in the exit frit reduces some of the quinones as the latter exits the column. This phenomenon is designated as the "concurrent anodic-cathodic response." It is also observed for quinones of of 3,4-dihydroxybenzoic acid and probably occurs with o- or p-quinones of other dihydroxyphenyl compounds. The use of nonferrous components in LC systems is recommended to eliminate possible on-column reduction of quinones.
Temperature of Steel Columns under Natural Fire
Directory of Open Access Journals (Sweden)
F. Wald
2004-01-01
Full Text Available Current fire design models for time-temperature development within structural elements as well as for structural behaviour are based on isolated member tests subjected to standard fire regimes, which serve as a reference heating, but do not model natural fire. Only tests on a real structure under a natural fire can evaluate future models of the temperature developments in a fire compartment, of the transfer of heat into the structure and of the overall structural behaviour under fire.To study overall structural behaviour, a research project was conducted on an eight storey steel frame building at the Cardington Building Research Establishment laboratory on January 16, 2003. A fire compartment 11×7 m was prepared on the fourth floor. A fire load of 40 kg/m2 was applied with 100 % permanent mechanical load and 65 % of imposed load. The paper summarises the experimental programme and shows the temperature development of the gas in the fire compartment and of the fire protected columns bearing the unprotected floors.
Selective detachment process in column flotation froth
Energy Technology Data Exchange (ETDEWEB)
Honaker, R.Q.; Ozsever, A.V.; Parekh, B.K. [University of Kentucky, Lexington, KY (United States). Dept. of Mining Engineering
2006-05-15
The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well-known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were quantified for particles in an anthracite coal that have a wide range of floatability potential. For highly floatable particles, froth recovery had a very minimal impact on overall recovery while the recovery of weakly floatable material was decreased substantially by reductions in froth recovery values. In addition, under carrying-capacity limiting conditions, selectivity was enhanced by the preferential detachment of the weakly floatable material. Based on this concept, highly floatable material was added directly into the froth zone when treating the anthracite coal. The enriched froth phase reduced the product ash content of the anthracite product by five absolute percentage points while maintaining a constant recovery value.
SPR Hydrostatic Column Model Verification and Validation.
Energy Technology Data Exchange (ETDEWEB)
Bettin, Giorgia [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lord, David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rudeen, David Keith [Gram, Inc. Albuquerque, NM (United States)
2015-10-01
A Hydrostatic Column Model (HCM) was developed to help differentiate between normal "tight" well behavior and small-leak behavior under nitrogen for testing the pressure integrity of crude oil storage wells at the U.S. Strategic Petroleum Reserve. This effort was motivated by steady, yet distinct, pressure behavior of a series of Big Hill caverns that have been placed under nitrogen for extended period of time. This report describes the HCM model, its functional requirements, the model structure and the verification and validation process. Different modes of operation are also described, which illustrate how the software can be used to model extended nitrogen monitoring and Mechanical Integrity Tests by predicting wellhead pressures along with nitrogen interface movements. Model verification has shown that the program runs correctly and it is implemented as intended. The cavern BH101 long term nitrogen test was used to validate the model which showed very good agreement with measured data. This supports the claim that the model is, in fact, capturing the relevant physical phenomena and can be used to make accurate predictions of both wellhead pressure and interface movements.
GPR Diagnostics of columns in archaeological contexts
Soldovieri, Francesco; Masini, Nicola; Persico, Raffaele; Catapano, Ilaria
2017-04-01
In the last decade the use of Ground Penetrating radar (GPR) applied to cultural heritage has been strongly increasing thanks to both technological development of sensors and softwares for data processing and cultural reasons such as the increasing awareness of conservators and archaeologist of the benefits of this method in terms of reduction of costs and time and risk associated with restoration works. This made GPR a mature technique for investigating different types of works of art and building elements of historical interest, including masonry structures, frescoes, mosaics [1-3], in the context of scientific projects, decision support activities aimed at the diagnosis of decay pathologies, and educational activities. One of the most complex building elements to be investigated by GPR are the columns both for the geometry of the object and for the several expected features to be detected including fractures, dishomogeneities and metallic connection elements. The work deals with the Ground Penetrating Radar diagnostic surveys at the prestigious archaeological site of Pompei. In particular, GPR surveys were carried out in two different areas, Palestra Grande and Tempio di Giove. The first campaign was carried out also as educational activity of the "International School "GEOPHYSICS AND REMOTE SENSING FOR ARCHAEOLOGY". The School aimed at giving the opportunity to scholars, PhD students, researchers and specialists in Geophysics, Remote Sensing and Archaeology to deepen their knowledge and expertise with geophysical and remote sensing techniques for archaeology and cultural heritage documentation and management. This survey was carried on two kinds of columns, with circular and rectangular section in order to detect possible hidden defects affecting their integrity. The second survey was carried out at Tempio di Giove, on request of the Soprintendenza Pompei, in order to gain information about the presence of reinforcement structures, which may be put inside the
Water column methanotrophy controlled by a rapid oceanographic switch
Steinle, L.; Graves, C.A.; Treude, T.; Ferré, B.; Biastoch, A.; Bussmann, I.; Berndt, C.; Krastel, S.; James, R.H.; Behrens, E.; Böning, C.W.; Greinert, J.; Sapart, C.-J.; Scheinert, M.; Sommer, S.; Lehmann, M.F.; Niemann, H.
2015-01-01
From the seabed to the water column, where it may be consumed by aerobic methanotrophic bacteria. The size and activity of methanotrophic communities, which determine the amount of methane consumed in the water column,are thought to be mainly controlled by nutrient and redoxdynamics3–7. Here, we
Comparison of monolithic silica and polymethacrylate capillary columns for LC
Czech Academy of Sciences Publication Activity Database
Moravcová, D.; Jandera, P.; Urban, J.; Planeta, Josef
2004-01-01
Roč. 27, 10-11 (2004), s. 789-800 ISSN 1615-9306 R&D Projects: GA ČR(CZ) GA203/02/0023 Keywords : monolithic column s * capillary HPLC * column testing Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 1.927, year: 2004
Alpha-contained laboratory scale pulse column facility for SRL
International Nuclear Information System (INIS)
Reif, D.J.; Cadieux, J.R.; Fauth, D.J.; Thompson, M.C.
1980-01-01
For studying solvent extraction processes, a laboratory-sized pulse column facility was constructed at the Savannah River Laboratory. This facility, in conjunction with existing miniature mixer-settler equipment and the centrifugal contactor facility currently under construction at SRL, provides capability for cross comparison of solvent extraction technology. This presentation describes the design and applications of the Pulse Column Facility at SRL
Hydrodynamic chromatography of polystyrene microparticles in micropillar array columns
Op de Beeck, Jeff; de Malsche, Wim; Vangelooven, Joris; Gardeniers, Johannes G.E.; Desmet, Gert
2010-01-01
We report on the possibility to perform HDC in micropillar array columns and the potential advantages of such a system. The HDC performance of a pillar array column with pillar diameter = 5 μm and an interpillar distance of 2.5 μm has been characterized using both a low MW tracer (FITC) and
Simulators of tray distillation columns as tools for interpreting ...
African Journals Online (AJOL)
... at 0.05 m intervals were determined from top to the bottom of simulators of tray distillation columns exposed to 20 mCi of 137 Cs. Signals generated from the simulators were identical with the experimental signals obtained from the Stabilizer Column of the crude oil distillation unit at the Tema Oil Refinery Ghana Limited.
Ultrasonic testing device having an adjustable water column
Roach, Dennis P.; Neidigk, Stephen O.; Rackow, Kirk A.; Duvall, Randy L.
2015-09-01
An ultrasonic testing device having a variable fluid column height is disclosed. An operator is able to adjust the fluid column height in real time during an inspection to to produce optimum ultrasonic focus and separate extraneous, unwanted UT signals from those stemming from the area of interest.
Dynamic stability of a lightly damped column trapped by a ...
African Journals Online (AJOL)
In this paper we initiate an analytical approach for determining the dynamic buckling load of a finite viscously damped column acted upon by a harmonically slowly varying explicitly time dependent load. The viscous damping is considered light and the column rests on an elastic foundation that produces a nonlinear ...
Localized giant cell tumors in the spinal column radiologic presentation
International Nuclear Information System (INIS)
Fernandez Echeverria, M.A.; Parra Blanco, J.A.; Pagola Serrano, M.A.; Mellado Santos, J.M.; Bueno Lopez, J.; Gonzalez Tutor, A.
1994-01-01
Given the uncommonness of the location of giant cell tumors (GCT) in the spinal column and the limited number of studies published, we present a case of GCT located in the spinal column, which involved both vertebral bodies and partially destroyed the adjacent rib. (Author)
Monitoring aged reversed-phase high performance liquid chromatography columns
Bolck, A; Smilde, AK; Bruins, CHP
1999-01-01
In this paper, a new approach for the quality assessment of routinely used reversed-phase high performance liquid chromatography columns is presented. A used column is not directly considered deteriorated when changes in retention occur. If attention is paid to the type and magnitude of the changes,
Nondestructive evaluation of warm mix asphalt through resonant column testing.
2014-02-01
Non-destructive testing has been used for decades to characterize engineering properties of hot-mix asphalt. Among such tests is the resonant column (RC) test, which is commonly used to characterize soil materials. The resonant column device at Penn ...
Retrofit of distillation columns in biodiesel production plants
International Nuclear Information System (INIS)
Nguyen, Nghi; Demirel, Yasar
2010-01-01
Column grand composite curves and the exergy loss profiles produced by the Column-Targeting Tool of the Aspen Plus simulator are used to assess the performance of the existing distillation columns, and reduce the costs of operation by appropriate retrofits in a biodiesel production plant. Effectiveness of the retrofits is assessed by means of thermodynamics and economic improvements. We have considered a biodiesel plant utilizing three distillation columns to purify biodiesel (fatty acid methyl ester) and byproduct glycerol as well as reduce the waste. The assessments of the base case simulation have indicated the need for modifications for the distillation columns. For column T202, the retrofits consisting of a feed preheating and reflux ratio modification have reduced the total exergy loss by 47%, while T301 and T302 columns exergy losses decreased by 61% and 52%, respectively. After the retrofits, the overall exergy loss for the three columns has decreased from 7491.86 kW to 3627.97 kW. The retrofits required a fixed capital cost of approximately $239,900 and saved approximately $1,900,000/year worth of electricity. The retrofits have reduced the consumption of energy considerably, and leaded to a more environmentally friendly operation for the biodiesel plant considered.
Dynamics and Control of Distillation Columns - A Critical Survey
Directory of Open Access Journals (Sweden)
Sigurd Skogestad
1997-07-01
Full Text Available Distillation column dynamics and control have been viewed by many as a very mature or even dead field. However, as is discussed in this paper significant new results have appeared over the last 5-10 years. These results include multiple steady states and instability in simple columns with ideal thermodynamics (which was believed to be impossible, the understanding of the difference between various control configurations and the systematic transformation between these, the feasibility of using the distillate-bottom structure, for control (which was believed to be impossible, the importance of flow dynamics for control studies, the fundamental problems in identifying models from open-loops responses, the use of simple regression estimators to estimate composition from temperatures, and an improved general understanding of the dynamic behavior of distillation columns which includes a better understanding of the fundamental difference between internal and external flow, simple formulas for estimating the dominant time constant, and a derivation of the linearizing effect of logarithmic transformations. These issues apply to all columns, even for ideal mixtures and simple columns with only two products. In addition, there have been significant advances for cases with complex thermodynamics and complex column configurations. These include the behavior and control of azeotropic distillation columns, and the possible complex dynamics of nonideal mixtures and of interlinked columns. However, both for the simple and more complex cases there are still a number of areas where further research is needed.
Gas chromatographic column for the Viking 1975 molecular analysis experiment
Novotny, M.; Hayes, J. M.; Bruner, F.; Simmonds, P. G.
1975-01-01
A gas chromatographic column has been developed for use in the remote analysis of the Martian surface. The column, which utilizes a liquid-modified organic adsorbent (Tenax) as the stationary phase, provides efficient transmission and resolution of nanogram quantities of organic materials in the presence of millionfold excesses of water and carbon dioxide.
Cow-in-a-Column – A Synthetic Food Replicator
National Aeronautics and Space Administration — The project tested the concept for combining waste degradation and food production in a single reactor or column, i.e., a "Cow-in-a-Column". The inputs could...
A Modeling Framework for Conventional and Heat Integrated Distillation Columns
DEFF Research Database (Denmark)
Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens
2013-01-01
In this paper, a generic, modular model framework for describing fluid separation by distillation is presented. At present, the framework is able to describe a conventional distillation column and a heat-integrated distillation column, but due to a modular structure the database can be further...
Graph Modelling Approach: Application to a Distillation Column
DEFF Research Database (Denmark)
Hovelaque, V.; Commault, C.; Bahar, Mehrdad
1997-01-01
Introduction, structured systems and digraphs, distillation column model, generic input-output decoupling problem, generic disturbance rejection problem, concluding remarks.......Introduction, structured systems and digraphs, distillation column model, generic input-output decoupling problem, generic disturbance rejection problem, concluding remarks....
HEAT TRANSFER ANALYSIS FOR FIXED CST AND RF COLUMNS
International Nuclear Information System (INIS)
Lee, S
2007-01-01
In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, transient and steady state two-dimensional heat transfer models have been constructed for columns loaded with cesium-saturated crystalline silicotitanate (CST) or spherical Resorcinol-Formaldehyde (RF) beads and 6 molar sodium tank waste supernate. Radiolytic decay of sorbed cesium results in heat generation within the columns. The models consider conductive heat transfer only with no convective cooling and no process flow within the columns (assumed column geometry: 27.375 in ID with a 6.625 in OD center-line cooling pipe). Heat transfer at the column walls was assumed to occur by natural convection cooling with 35 C air. A number of modeling calculations were performed using this computational heat transfer approach. Minimal additional calculations were also conducted to predict temperature increases expected for salt solution processed through columns of various heights at the slowest expected operational flow rate of 5 gpm. Results for the bounding model with no process flow and no active cooling indicate that the time required to reach the boiling point of ∼130 C for a CST-salt solution mixture containing 257 Ci/liter of Cs-137 heat source (maximum expected loading for SCIX applications) at 35 C initial temperature is about 6 days. Modeling results for a column actively cooled with external wall jackets and the internal coolant pipe (inlet coolant water temperature: 25 C) indicate that the CST column can be maintained non-boiling under these conditions indefinitely. The results also show that the maximum temperature of an RF-salt solution column containing 133 Ci/liter of Cs-137 (maximum expected loading) will never reach boiling under any conditions (maximum predicted temperature without cooling: 88 C). The results indicate that a 6-in cooling pipe at the center of the column provides the most effective cooling mechanism for reducing the maximum
Characterization of retentivity of reversed phase liquid chromatography columns.
Ying, P T; Dorsey, J G
1991-03-01
There are dozens of commercially available reversed phase columns, most marketed as C-8 or C-18 materials, but with no useful way of classifying their retentivity. A useful way of ranking these columns in terms of column "strength" or retentivity is presented. The method utilizes a value for ln k'(w), the estimated retention of a solute from a mobile phase of 100% water, and the slope of the plot of ln k' vsE(T)(30), the solvent polarity. The method is validated with 26 solutes varying in ln k'(w) from about 2 to over 20, on 14 different reversed phase columns. In agreement with previous work, it is found that the phase volume ratio of the column is the most important parameter in determining retentivity. It is strongly suggested that manufacturers adopt a uniform method of calculating this value and that it be made available in advertising, rather than the uninterpretable "% carbon".
A Modelling Framework for Conventional and Heat Integrated Distillation Columns
DEFF Research Database (Denmark)
Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens
2013-01-01
of hydrocarbons such as separations of equimolar mixtures of benzene/toluene or propane/propene described by simple models, a generic, modular, model framework is presented in this work. At present, the framework is able to describe a conventional distillation column, a mechanical vapor recompression column......Diabatic operation of distillation columns can lead to signicant reductions in energy utilization and operation cost compared to conventional (adiabatic) distillation columns, at an expense of an increased complexity of design and operation. The earliest diabatic distillation conguration dates back...... to the late 70s, and various dierent congurations have appeared since. However, at present, no full-scale diabatic distillation columns are currently operating in the industry. Current studies related to alternative distillation congurations report very dierent gures for potential energy savings which...
Cesium ion exchange using actual waste: Column size considerations
International Nuclear Information System (INIS)
Brooks, K.P.
1996-04-01
It is presently planned to remove cesium from Hanford tank waste supernates and sludge wash solutions using ion exchange. To support the development of a cesium ion exchange process, laboratory experiments produced column breakthrough curves using wastes simulants in 200 mL columns. To verify the validity of the simulant tests, column runs with actual supernatants are being planned. The purpose of these actual waste tests is two-fold. First, the tests will verify that use of the simulant accurately reflects the equilibrium and rate behavior of the resin compared to actual wastes. Batch tests and column tests will be used to compare equilibrium behaviors and rate behaviors, respectively. Second, the tests will assist in clarifying the negative interactions between the actual waste and the ion exchange resin, which cannot be effectively tested with simulant. Such interactions include organic fouling of the resin and salt precipitation in the column. These effects may affect the shape of the column breakthrough curve. The reduction in column size also may change the shape of the curve, making the individual effects even more difficult to sort out. To simplify the evaluation, the changes due to column size must be either understood or eliminated. This report describes the determination of the column size for actual waste testing that best minimizes the effect of scale-down. This evaluation will provide a theoretical basis for the dimensions of the column. Experimental testing is still required before the final decision can be made. This evaluation will be confined to the study of CS-100 and R-F resins with NCAW simulant and to a limited extent DSSF waste simulant. Only the cesium loading phase has been considered
Hemifield columns co-opt ocular dominance column structure in human achiasma.
Olman, Cheryl A; Bao, Pinglei; Engel, Stephen A; Grant, Andrea N; Purington, Chris; Qiu, Cheng; Schallmo, Michael-Paul; Tjan, Bosco S
2018-01-01
In the absence of an optic chiasm, visual input to the right eye is represented in primary visual cortex (V1) in the right hemisphere, while visual input to the left eye activates V1 in the left hemisphere. Retinotopic mapping In V1 reveals that in each hemisphere left and right visual hemifield representations are overlaid (Hoffmann et al., 2012). To explain how overlapping hemifield representations in V1 do not impair vision, we tested the hypothesis that visual projections from nasal and temporal retina create interdigitated left and right visual hemifield representations in V1, similar to the ocular dominance columns observed in neurotypical subjects (Victor et al., 2000). We used high-resolution fMRI at 7T to measure the spatial distribution of responses to left- and right-hemifield stimulation in one achiasmic subject. T 2 -weighted 2D Spin Echo images were acquired at 0.8mm isotropic resolution. The left eye was occluded. To the right eye, a presentation of flickering checkerboards alternated between the left and right visual fields in a blocked stimulus design. The participant performed a demanding orientation-discrimination task at fixation. A general linear model was used to estimate the preference of voxels in V1 to left- and right-hemifield stimulation. The spatial distribution of voxels with significant preference for each hemifield showed interdigitated clusters which densely packed V1 in the right hemisphere. The spatial distribution of hemifield-preference voxels in the achiasmic subject was stable between two days of testing and comparable in scale to that of human ocular dominance columns. These results are the first in vivo evidence showing that visual hemifield representations interdigitate in achiasmic V1 following a similar developmental course to that of ocular dominance columns in V1 with intact optic chiasm. Copyright © 2017 Elsevier Inc. All rights reserved.
Column Grid Array Rework for High Reliability
Mehta, Atul C.; Bodie, Charles C.
2008-01-01
Due to requirements for reduced size and weight, use of grid array packages in space applications has become common place. To meet the requirement of high reliability and high number of I/Os, ceramic column grid array packages (CCGA) were selected for major electronic components used in next MARS Rover mission (specifically high density Field Programmable Gate Arrays). ABSTRACT The probability of removal and replacement of these devices on the actual flight printed wiring board assemblies is deemed to be very high because of last minute discoveries in final test which will dictate changes in the firmware. The questions and challenges presented to the manufacturing organizations engaged in the production of high reliability electronic assemblies are, Is the reliability of the PWBA adversely affected by rework (removal and replacement) of the CGA package? and How many times can we rework the same board without destroying a pad or degrading the lifetime of the assembly? To answer these questions, the most complex printed wiring board assembly used by the project was chosen to be used as the test vehicle, the PWB was modified to provide a daisy chain pattern, and a number of bare PWB s were acquired to this modified design. Non-functional 624 pin CGA packages with internal daisy chained matching the pattern on the PWB were procured. The combination of the modified PWB and the daisy chained packages enables continuity measurements of every soldered contact during subsequent testing and thermal cycling. Several test vehicles boards were assembled, reworked and then thermal cycled to assess the reliability of the solder joints and board material including pads and traces near the CGA. The details of rework process and results of thermal cycling are presented in this paper.
Column-by-column compositional mapping by Z-contrast imaging
Energy Technology Data Exchange (ETDEWEB)
Molina, S.I. [Departamento de Ciencia de los Materiales e I.M. y Q.I., Facultad de Ciencias, Universidad de Cadiz, Campus Rio San Pedro, s/n, 11510 Puerto Real, Cadiz (Spain)], E-mail: sergio.molina@uca.es; Sales, D.L. [Departamento de Ciencia de los Materiales e I.M. y Q.I., Facultad de Ciencias, Universidad de Cadiz, Campus Rio San Pedro, s/n, 11510 Puerto Real, Cadiz (Spain); Galindo, P.L. [Departamento de Lenguajes y Sistemas Informaticos, CASEM, Universidad de Cadiz, Campus Rio San Pedro, s/n, 11510 Puerto Real, Cadiz (Spain); Fuster, D.; Gonzalez, Y.; Alen, B.; Gonzalez, L. [Instituto de Microelectronica de Madrid (CNM, CSIC), Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain); Varela, M.; Pennycook, S.J. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)
2009-01-15
A phenomenological method is developed to determine the composition of materials, with atomic column resolution, by analysis of integrated intensities of aberration-corrected Z-contrast scanning transmission electron microscopy images. The method is exemplified for InAs{sub x}P{sub 1-x} alloys using epitaxial thin films with calibrated compositions as standards. Using this approach we have determined the composition of the two-dimensional wetting layer formed between self-assembled InAs quantum wires on InP(0 0 1) substrates.
International Nuclear Information System (INIS)
Qin Wei; Dai Youyuan; Wang Jiading
1994-01-01
Annular pulsed extraction column can successfully provide large throughput and can be made critically safe for fuel reprocessing. This investigation is to study the two phase flow characteristics in annular pulsed extraction column with four different annular width. 30% TBP (in kerosene)-water is used (water as continuous phase). Results show that modified Pratt correlation is valid under the experimental operation conditions for the annular pulsed extraction column. The characteristic velocity U K decreased with the increase of energy input and increased with the increase of the ratio of annular width to column diameter. Flooding velocity correlation is suggested. The deviation of the calculated values from the experimental data is within +20% for four annular width in a pulsed extraction column
Cervical column morphology and craniofacial profiles in monozygotic twins.
Sonnesen, Liselotte; Pallisgaard, Carsten; Kjaer, Inger
2008-02-01
Previous studies have described the relationships between cervical column morphology and craniofacial morphology. The aims of the present study were to describe cervical column morphology in 38 pairs of adult monozygotic (MZ) twins, and compare craniofacial morphology in twins with fusions with craniofacial morphology in twins without fusion. Visual assessment of cervical column morphology and cephalometric measurements of craniofacial morphology were performed on profile radiographs. In the cervical column, fusion between corpora of the second and third vertebrae was registered as fusion. In the twin group, 8 twin pairs had fusion of the cervical column in both individuals within the pair (sub-group A), 25 pairs had no fusions (subgroup B), and in 5 pairs, cervical column morphology was different within the pair (subgroup C), as one twin had fusion and the other did not. Comparison of craniofacial profiles showed a tendency to increased jaw retrognathia, larger cranial base angle, and larger mandibular inclination in subgroup A than in subgroup B. The same tendency was observed within subgroup C between the individual twins with fusion compared with those without fusion. These results confirm that cervical fusions and craniofacial morphology may be interrelated in twins when analysed on profile radiographs. The study also documents that differences in cervical column morphology can occur in individuals within a pair of MZ twins. It illustrates that differences in craniofacial morphology between individuals within a pair of MZ twins can be associated with cervical fusion.
Strength degradation of oxidized graphite support column in VHTR
International Nuclear Information System (INIS)
Park, Byung Ha; No, Hee Cheon
2010-01-01
Air-ingress events caused by large pipe breaks are important accidents considered in the design of Very High Temperature Gas-Cooled Reactors (VHTRs). A main safety concern for this type of event is the possibility of core collapse following the failure of the graphite support column, which can be oxidized by ingressed air. In this study, the main target is to predict the strength of the oxidized graphite support column. Through compression tests for fresh and oxidized graphite columns, the compressive strength of IG-110 was obtained. The buckling strength of the IG-110 column is expressed using the following empirical straight-line formula: σ cr,buckling =91.34-1.01(L/r). Graphite oxidation in Zone 1 is volume reaction and that in Zone 3 is surface reaction. We notice that the ultimate strength of the graphite column oxidized in Zones 1 and 3 only depends on the slenderness ratio and bulk density. Its strength degradation oxidized in Zone 1 is expressed in the following nondimensional form: σ/σ 0 =exp(-kd), k=0.114. We found that the strength degradation of a graphite column, oxidized in Zone 3, follows the above buckling empirical formula as the slenderness of the column changes. (author)
Behaviour of normal reinforced concrete columns exposed to different soils
Directory of Open Access Journals (Sweden)
Rasheed Laith
2018-01-01
Full Text Available Concrete resistance to sulfate attack is one of the most important characteristics for maintaining the durability of concrete. In this study, the effect of the attack of sulfate salts on normal reinforced concrete column was investigated by burying these columns in two types of soils (sandy and clayey in two pits at a depth of 3 m in one of the agricultural areas in the holy city of Karbala, one containing sandy soil (SO3 = 10.609% and the other containing clayey soil with (SO3 = 2.61%. The tests were used (pure axial compression test of reinforced concrete columns, compressive strength test, and splitting tensile strength test, absorption, voids ratio and finally density. It`s found that the strength of RC columns decreasing by (12.51% for age (240 days, for columns buried in clayey soil, where the strength increased by (11.71% for the same period, for columns buried in sandy soils, with respect to the reference column.
Modeling atrazine transport in soil columns with HYDRUS-1D
Directory of Open Access Journals (Sweden)
John Leju Celestino Ladu
2011-09-01
Full Text Available Both physical and chemical processes affect the fate and transport of herbicides. It is useful to simulate these processes with computer programs to predict solute movement. Simulations were run with HYDRUS-1D to identify the sorption and degradation parameters of atrazine through calibration from the breakthrough curves (BTCs. Data from undisturbed and disturbed soil column experiments were compared and analyzed using the dual-porosity model. The study results show that the values of dispersivity are slightly lower in disturbed columns, suggesting that the more heterogeneous the structure is, the higher the dispersivity. Sorption parameters also show slight variability, which is attributed to the differences in soil properties, experimental conditions and methods, or other ecological factors. For both of the columns, the degradation rates were similar. Potassium bromide was used as a conservative non-reactive tracer to characterize the water movement in columns. Atrazine BTCs exhibited significant tailing and asymmetry, indicating non-equilibrium sorption during solute transport. The dual-porosity model was verified to best fit the BTCs of the column experiments. Greater or lesser concentration of atrazine spreading to the bottom of the columns indicated risk of groundwater contamination. Overall, HYDRUS-1D successfully simulated the atrazine transport in soil columns.
Stability of embankments over cement deep soil mixing columns
International Nuclear Information System (INIS)
Morilla Moar, P.; Melentijevic, S.
2014-01-01
The deep soil mixing (DSM) is one of the ground improvement methods used for the construction of embankments over soft soils. DSM column-supported embankments are constructed over soft soils to accelerate its construction, improve embankment stability, increase bearing capacity and control of total and differential settlements. There are two traditional design methods, the Japanese (rigid columns) and the scandinavian (soft and semi-rigid columns). Based on Laboratory analysis and numerical analysis these traditional approaches have been questioned by several authors due to its overestimation of the embankment stability considering that the most common failures types are not assumed. This paper presents a brief review of traditional design methods for embankments on DSM columns constructed in soft soils, studies carried out determine the most likely failure types of DSM columns, methods to decrease the overestimation when using limit equilibrium methods and numerical analysis methods that permit detect appropriate failure modes in DSM columns. Finally a case study was assessed using both limited equilibrium and finite element methods which confirmed the overestimation in the factors of safety on embankment stability over DSM columns. (Author)
Reliability assessment of slender concrete columns at the stability failure
Valašík, Adrián; Benko, Vladimír; Strauss, Alfred; Täubling, Benjamin
2018-01-01
The European Standard for designing concrete columns within the use of non-linear methods shows deficiencies in terms of global reliability, in case that the concrete columns fail by the loss of stability. The buckling failure is a brittle failure which occurs without warning and the probability of its formation depends on the columns slenderness. Experiments with slender concrete columns were carried out in cooperation with STRABAG Bratislava LTD in Central Laboratory of Faculty of Civil Engineering SUT in Bratislava. The following article aims to compare the global reliability of slender concrete columns with slenderness of 90 and higher. The columns were designed according to methods offered by EN 1992-1-1 [1]. The mentioned experiments were used as basis for deterministic nonlinear modelling of the columns and subsequent the probabilistic evaluation of structural response variability. Final results may be utilized as thresholds for loading of produced structural elements and they aim to present probabilistic design as less conservative compared to classic partial safety factor based design and alternative ECOV method.
Internet delivered question and answer column for patients with schizophrenia.
Maijala, Riikka; Anttila, Minna; Koivunen, Marita; Pitkänen, Anneli; Kuosmanen, Lauri; Välimäki, Maritta
2015-01-01
The purpose of this study was to describe the use of an Internet delivered question and answer column among patients with schizophrenia. The column was developed for research purposes. The study sample consisted of patients (N = 100) admitted to acute inpatient psychiatric care in two hospital districts. Descriptive data were collected from the column to which a nurse replied within 3 days and analysed using qualitative content analysis. The column had four to five questions weekly. The most common age of users was 18-24 years, and the gender distribution was almost equal. Column use was heaviest among students (44%) and least among unemployed people (19%). Out of 85 questions or comments sent to the column, 25 (29%) were related to program training and the remaining 60 (71%) were related to medication (31%), illness and tests (25%), other questions or comments (9%), daily life and coping with it (4%), and places to receive treatment (2%). An Internet delivered question and answer column can be included in the care of patients with schizophrenia. However, it requires a new type of basic and additional education in the field of mental health care in order for nurses to be able to provide nursing via the Internet forum.
Effects of Irregular Bridge Columns and Feasibility of Seismic Regularity
Thomas, Abey E.
2018-05-01
Bridges with unequal column height is one of the main irregularities in bridge design particularly while negotiating steep valleys, making the bridges vulnerable to seismic action. The desirable behaviour of bridge columns towards seismic loading is that, they should perform in a regular fashion, i.e. the capacity of each column should be utilized evenly. But, this type of behaviour is often missing when the column heights are unequal along the length of the bridge, allowing short columns to bear the maximum lateral load. In the present study, the effects of unequal column height on the global seismic performance of bridges are studied using pushover analysis. Codes such as CalTrans (Engineering service center, earthquake engineering branch, 2013) and EC-8 (EN 1998-2: design of structures for earthquake resistance. Part 2: bridges, European Committee for Standardization, Brussels, 2005) suggests seismic regularity criterion for achieving regular seismic performance level at all the bridge columns. The feasibility of adopting these seismic regularity criterions along with those mentioned in literatures will be assessed for bridges designed as per the Indian Standards in the present study.
Experimental and theoretical investigation of column - flat slab joint ductility
International Nuclear Information System (INIS)
Iskhakov, I.; Ribakov, Y.; Shah, A.
2009-01-01
Most modern seismic codes use ductility as one of the basic design parameters. Actually, ductility defines the ability of a structure or its elements to absorb energy by plastic deformations. Until the end of the previous century ductility was defined qualitatively. Most research works related to ductility are focused on structural elements' sections. This study was aimed at complex experimental and theoretical investigation of flat slab-column joints ductility. It is one of the first attempts to obtain quantitative values of joint's ductility for the case of high strength concrete columns and normal strength concrete slabs. It was shown that the flat slab-column joint is a three-dimension (3D) element and its ductility in horizontal and vertical directions are different. This is the main difference between ductility of elements and joint ductility. In case of flat slab-column joints, essential contribution to joint's ductility can be obtained due to the slab's confining effect. Based on experimental data, the authors demonstrate that flat slab-column joint's ductility depends on the joint's confining effect in two horizontal and vertical directions. Furthermore, the influence of slab load intensity and slab reinforcement ratio on the joint's ductility is performed in this study. It is also demonstrated that the effect of the ratio between the slab thickness and the column's section dimension on the ductility parameter is significant. Equations for obtaining a quantitative value of a flat slab-column joint's ductility parameter were developed.
Investigation of Gas Holdup in a Vibrating Bubble Column
Mohagheghian, Shahrouz; Elbing, Brian
2015-11-01
Synthetic fuels are part of the solution to the world's energy crisis and climate change. Liquefaction of coal during the Fischer-Tropsch process in a bubble column reactor (BCR) is a key step in production of synthetic fuel. It is known from the 1960's that vibration improves mass transfer in bubble column. The current study experimentally investigates the effect that vibration frequency and amplitude has on gas holdup and bubble size distribution within a bubble column. Air (disperse phase) was injected into water (continuous phase) through a needle shape injector near the bottom of the column, which was open to atmospheric pressure. The air volumetric flow rate was measured with a variable area flow meter. Vibrations were generated with a custom-made shaker table, which oscillated the entire column with independently specified amplitude and frequency (0-30 Hz). Geometric dependencies can be investigated with four cast acrylic columns with aspect ratios ranging from 4.36 to 24, and injector needle internal diameters between 0.32 and 1.59 mm. The gas holdup within the column was measured with a flow visualization system, and a PIV system was used to measure phase velocities. Preliminary results for the non-vibrating and vibrating cases will be presented.
Comments on Simplified Calculation Method for Fire Exposed Concrete Columns
DEFF Research Database (Denmark)
Hertz, Kristian Dahl
1998-01-01
The author has developed new simplified calculation methods for fire exposed columns. Methods, which are found In ENV 1992-1-2 chapter 4.3 and in proposal for Danish code of Practise DS411 chapter 9. In the present supporting document the methods are derived and 50 eccentrically loaded fire expos...... columns are calculated and compared to results of full-scale tests. Furthermore 500 columns are calculated in order to present each test result related to a variation of the calculation in time of fire resistance....
Study on Predicting Axial Load Capacity of CFST Columns
Ravi Kumar, H.; Muthu, K. U.; Kumar, N. S.
2017-11-01
This work presents an analytical study and experimental study on the behaviour and ultimate load carrying capacity of axially compressed self-compacting concrete-filled steel tubular columns. Results of tests conducted by various researchers on 213 samples concrete-filled steel tubular columns are reported and present authors experimental data are reported. Two theoretical equations were derived for the prediction of the ultimate axial load strength of concrete-filled steel tubular columns. The results from prediction were compared with the experimental data. Validation to the experimental results was made.
Numerical Simulation of Fluid Dynamics in a Monolithic Column
Directory of Open Access Journals (Sweden)
Kazuhiro Yamamoto
2017-01-01
Full Text Available As for the measurement of polycyclic aromatic hydrocarbons (PAHs, ultra-performance liquid chromatography (UPLC is used for PAH identification and densitometry. However, when a solvent containing a substance to be identified passes through a column of UPLC, a dedicated high-pressure-proof device is required. Recently, a liquid chromatography instrument using a monolithic column technology has been proposed to reduce the pressure of UPLC. The present study tested five types of monolithic columns produced in experiments. To simulate the flow field, the lattice Boltzmann method (LBM was used. The velocity profile was discussed to decrease the pressure drop in the ultra-performance liquid chromatography (UPLC system.
SENSITIVITY ANALYSIS FOR SALTSTONE DISPOSAL UNIT COLUMN DEGRADATION ANALYSES
Energy Technology Data Exchange (ETDEWEB)
Flach, G.
2014-10-28
PORFLOW related analyses supporting a Sensitivity Analysis for Saltstone Disposal Unit (SDU) column degradation were performed. Previous analyses, Flach and Taylor 2014, used a model in which the SDU columns degraded in a piecewise manner from the top and bottom simultaneously. The current analyses employs a model in which all pieces of the column degrade at the same time. Information was extracted from the analyses which may be useful in determining the distribution of Tc-99 in the various SDUs throughout time and in determining flow balances for the SDUs.
Partial Path Column Generation for the Vehicle Routing Problem
DEFF Research Database (Denmark)
Jepsen, Mads Kehlet; Petersen, Bjørn
This paper presents a column generation algorithm for the Capacitated Vehicle Routing Problem (CVRP) and the Vehicle Routing Problem with Time Windows (VRPTW). Traditionally, column generation models of the CVRP and VRPTW have consisted of a Set Partitioning master problem with each column...... of the giant tour’; a so-called partial path, i.e., not necessarily starting and ending in the depot. This way, the length of the partial path can be bounded and a better control of the size of the solution space for the pricing problem can be obtained....
Control structure selection for energy integrated distillation column
DEFF Research Database (Denmark)
Hansen, J.E.; Jørgensen, Sten Bay
1998-01-01
This paper treats a case study on control structure selection for an almost binary distillation column. The column is energy integrated with a heat pump in order to transfer heat from the condenser to the reboiler. This integrated plant configuration renders the possible control structures somewhat...... different from what is usual for binary distillation columns. Further the heat pump enables disturbances to propagate faster through the system. The plant has six possible actuators of which three must be used to stabilize the system. Hereby three actuators are left for product purity control. An MILP...
Impact of Holes on the Buckling of RHS Steel Column
Directory of Open Access Journals (Sweden)
Najla'a H. AL-Shareef
2018-03-01
Full Text Available This study presented an experimental and theoretical study on the effect of hole on the behavior of rectangular hollow steel columns subjected to axial compression load. Specimens were tested to investigated the ultimate capacity and the load- axial displacement behavior of steel columns. In this paper finite element analysis is done by using general purpose ANSYS 12.0 to investigate the behavior of rectangular hollow steel column with hole. In the experimental work, rectangular hollow steel columns with rounded corners were used in the constriction of the specimens which have dimensions of cross section (50*80mm and height of (250 and 500mm with thickness of (1.25,4 and 6mm with hole ((α*80*80mm when α is equal to (0.2,0.4,0.6 and 0.8. Twenty four columns under compression load were tested in order to investigate the effect of hole on the ultimate load of rectangular hollow steel column. The experimental results indicated that the typical failure mode for all the tested hollow specimen was the local buckling. The tested results indicated that the increasing of hole dimension leads to reduction in ultimate loads of tested column to 75%. The results show the reducing of load by 94.7% due to decreasing the thickness of column while the hole size is constant (0.2*80*80. The buckling load decreases by 84.62% when hole position changes from Lo=0.25L to 0.75L. Holes can be made in the middle of column with dimension up to 0.4 of column's length. The AISC (2005 presents the values closest to the experimental results for the nominal yielding compressive strength. The effect for increasing of slendeness ratio and thickness to area ratio(t/A leading to decreacing the critical stresses and the failure of column with large size of hole and (t/A ratio less than 0.74% was due to lacal buckling while the global buckling failure was abserve for column with small size of hole and (t/A ratio above than 0.74%. The compersion between the experimental
Characterization of Bubble Size Distributions within a Bubble Column
Shahrouz Mohagheghian; Brian R. Elbing
2018-01-01
The current study experimentally examines bubble size distribution (BSD) within a bubble column and the associated characteristic length scales. Air was injected into a column of water via a single injection tube. The column diameter (63–102 mm), injection tube diameter (0.8–1.6 mm) and superficial gas velocity (1.4–55 mm/s) were varied. Large samples (up to 54,000 bubbles) of bubble sizes measured via 2D imaging were used to produce probability density functions (PDFs). The PDFs were used to...
International Nuclear Information System (INIS)
Lin, J C; Chang, T K; Yang, J H; Jeng, J H; Lee, D L; Jiang, S B
2009-01-01
Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAGE) process in the citrate bath. The surface morphology and chemical composition of the micro-columns were determined by copper concentration in the bath and by the electrical bias of MAGE. When fabricated in a bath of dilute copper (i.e. 4 mM) at lower voltages (e.g. 3.8 and 4.0 V), the alloy micro-columns revealed uniform diameter and smooth appearance. The alloy composition demonstrated an increase in the wt% ratio of Ni/Cu from 75/25, 80/20, 83/17 to 87/13 with increasing electrical bias from 3.8, 4.0, 4.2 to 4.4 V. However, it decreases from 75/25, 57/43 to 47/53 with increasing copper concentration from 4, 8 to 12 mM in the bath. Citrate plays a role in forming complexes with nickel and copper at similar reduction potentials, thus reducing simultaneously to Ni–Cu alloy. The mechanism for fabricating alloy micro-columns could be delineated on the basis of cathodic polarization of the complexes. A couple of micro-columns were fabricated using MAGE in constructing a pure copper micro-column on the top of a Ni/Cu (at 47/53) alloy micro-column. This micro-thermocouple provides a satisfactory measurement with good sensitivity and precision
Directory of Open Access Journals (Sweden)
Nelson López
2017-12-01
Full Text Available In this research, the nonlinear behavior of a real-scale experimental joint (node is studied, consisting of three reinforced concrete elements, one column and two beams joined to a structural steel column at the upper level. In the numerical analysis the model of the union was analyzed in the inelastic range, this model was elaborated with the finite element program based on fibers, SeismoStruct to analyze as a function of time, the traction and compression efforts in the confined area and not confined area of the concrete column and in the longitudinal reinforcement steel, as well as verification of the design of the base plate that joins the two columns. The results showed that tensile stresses in the unconfined zone surpassed the concrete breaking point, with cracking occurring just below the lower edge of the beams; in the confined area the traction efforts were much lower, with cracks occurring later than in the non-confined area. The concrete column-steel column joint behaved as a rigid node, so the elastic design was consistent with the calculation methodology of base plates for steel columns.
Permanent magnet finger-size scanning electron microscope columns
Energy Technology Data Exchange (ETDEWEB)
Nelliyan, K., E-mail: elenk@nus.edu.sg [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Khursheed, A. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore)
2011-07-21
This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.
EX1005 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1005: Guam to Honolulu, HI Transit...
Associations between the Cervical Vertebral Column and Craniofacial Morphology
DEFF Research Database (Denmark)
Sonnesen, Ane Liselotte
2010-01-01
Aim. To summarize recent studies on morphological deviations of the cervical vertebral column and associations with craniofacial morphology and head posture in nonsyndromic patients and in patients with obstructive sleep apnoea (OSA). Design. In these recent studies, visual assessment of the cerv......Aim. To summarize recent studies on morphological deviations of the cervical vertebral column and associations with craniofacial morphology and head posture in nonsyndromic patients and in patients with obstructive sleep apnoea (OSA). Design. In these recent studies, visual assessment...... of the cervical vertebral column and cephalometric analysis of the craniofacial skeleton were performed on profile radiographs of subjects with neutral occlusion, patients with severe skeletal malocclusions and patients with OSA. Material from human triploid foetuses and mouse embryos was analysed histologically....... Results. Recent studies have documented associations between fusion of the cervical vertebral column and craniofacial morphology, including head posture in patients with severe skeletal malocclusions. Histological studies on prenatal material supported these findings. Conclusion. It is suggested...
EX1701 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1701: Kingman/Palmyra, Jarvis (Mapping)...
EX1102 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1102: ROV and Camera Sled Integration...
EX1403 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1403: East Coast Mapping and Exploration...
Permanent magnet finger-size scanning electron microscope columns
International Nuclear Information System (INIS)
Nelliyan, K.; Khursheed, A.
2011-01-01
This paper presents permanent magnet scanning electron microscope (SEM) designs for both tungsten and field emission guns. Each column makes use of permanent magnet technology and operates at a fixed primary beam voltage. A prototype column operating at a beam voltage of 15 kV was made and tested inside the specimen chamber of a conventional SEM. A small electrostatic stigmator unit and dedicated scanning coils were integrated into the column. The scan coils were wound directly around the objective lens iron core in order to reduce its size. Preliminary experimental images of a test grid specimen were obtained through the prototype finger-size column, demonstrating that it is in principle feasible.
EX1104 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1104: Mid-Cayman Rise Exploration...
EX1204 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1204: Northeastern Canyons and...
EX1003 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1003: Transit from Hawaii to Guam...
EX0905 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0905: Mapping Field Trials II Mendocino...
Pulse amplitude and frequency effects in a pulsed packed column
International Nuclear Information System (INIS)
Russell, S.H.
1954-04-01
A study has been made of the effect on the efficiency and capacity of applying pulses of varying amplitude and frequency to a packed column. In the efficiency studies, the maximum efficiency was obtained with a pulse having an amplitude of 3/8'' and a frequency of 140 cycles per minute. Under these conditions, the column was about five times as efficient as a simple packed column. Two general types of results were obtained in the capacity studies. Under certain conditions, the capacity increased over that of a simple packed column, but under others, it decreased. Some of the factors causing this were investigated but the fundamental reasons were not determined due to a lack of personnel for the necessary experiments. (author)
Microchip-based monolithic column for high performance liquid chromatography
National Aeronautics and Space Administration — We have developed microchip based monolithic columns that can be used for liquid chromatography of small organic molecules, as well as, macromolecules such as...
Denitrification in the water column of the central Baltic Sea
DEFF Research Database (Denmark)
Dalsgaard, Tage; De Brabandere, Loreto; Hall, Per O. J.
2013-01-01
Removal of fixed nitrogen in the water column of the eastern Gotland Basin, central Baltic Sea, was studied during two cruises in September 2008 and August 2010. The water column was stratified with anoxic sulfidic bottom water meeting oxic nitrate containing water at the oxic–anoxic interface......3 or sulfide concentrations were converted to in situ rates using the measured water column concentrations of NO3 and sulfide and the actual measured relations between NO3 and sulfide concentrations and enitrification rates. In situ denitrification ranged from 0.24 to 15.9 nM N2 h1. Assuming...... area. Even with an active denitrification layer of 3–6 m thickness the pelagic denitrification per unit area clearly exceeded sediment denitrification rates elsewhere in the Baltic Sea. When extrapolated to the entire Baltic Proper (BP) denitrification in the water column was in the range of 132...
Groundwater arsenic remediation using zerovalent iron: Batch and column tests
Recently, increasing efforts have been made to explore the applicability and limitations of zerovalent iron (Fe0) for the treatment of arsenicbearing groundwater and wastewater. The experimental batch and column tests have demonstrated that arsenate and arsenite are removed effec...
EX1302 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1302: Ship Shakedown, Patch Test and...
Bubble column fermenter modeling: a comparison for pressure effects
Energy Technology Data Exchange (ETDEWEB)
Shioya, S; Dang, N D.P.; Dunn, I J
1978-01-01
Two models which describe the oxygen transfer, oxygen uptake, and axial mixing in a bubble column fermenter are described. Model I includes no pressure effects and can be solved analytically. Model II incorporates the influence of hydrostatic pressure on oxygen solubility and gas expansion and must be solved numerically. The liquid phase oxygen concentration profiles from both models are compared to ascertain for what parametric conditions and for what maximum column height Model I is valid. Results show that for many situations Model I can approximate the oxygen profiles in a 10 m column within 20%. As the transfer and uptake rates increase, the deviation of Model I can reach 80% for a 10 m column. 7 figures.
EX0802 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0802: Operation Halloween Shakedown...
EX1006 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1006: Hawaii to San Francisco Transit to...
EX0801 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0801: Mapping Operations Shakedown...
EX1603 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1603: Hohonu Moana: Exploring the Deep...
EX1604 Water Column Summary Report and Profile Data Collection
National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1604: CAPSTONE Wake Island PRIMNM...
Varied overstrain injuries of the vertebral column conditioned by evolution
Energy Technology Data Exchange (ETDEWEB)
Kohlbach, W
1983-08-01
During physiological growth of the juvenile vertebral column, various stages of stability occur which are characterized by the condition of the marginal rim of the vertebral bodies. If the vertebral juvenile column is overstrained, these variations in stability results in a variety of damage to vertebral bodies and vertebral disks. One of these lesions corresponds to Scheuermann's disease (osteochondrosis of vertebral epiphyses in juveniles). Damage of the vertebral column due to overstrain can occur only if the overstrain is applied in upright position. Since Man alone can damage his vertebral column in upright position (as a result of his evolutionary development), Scheuermann's thesis is confirmed that Scheuermann's disease is confined to Man. Spondylolysis/spondylolisthesis is also a damage caused by overstrain. Here, too, the damage can occur only if the load is exercised in upright position, with the exception of a slanted positioning of the intervertebral components.
Varied overstrain injuries of the vertebral column conditioned by evolution
International Nuclear Information System (INIS)
Kohlbach, W.
1983-01-01
During physiological growth of the juvenile vertebral column, various stages of stability occur which are characterized by the condition of the marginal rim of the vertebral bodies. If the vertebral juvenile column is overstrained, these variations in stability results in a variety of damage to vertebral bodies and vertebral disks. One of these lesions corresponds to Scheuermann's disease (osteochondrosis of vertebral epiphyses in juveniles). Damage of the vertebral column due to overstrain can occur only if the overstrain is applied in upright position. Since Man alone can damage his vertebral column in upright position (as a result of his evolutionary development), Scheuermann's thesis is confirmed that Scheuermann's disease is confined to Man. Spondylolysis/spondylolisthesis is also a damage caused by overstrain. Here, too, the damage can occur only if the load is exercised in upright position, with the exception of a slanted positioning of the intervertebral components. (orig.) [de
Science Column: Reconstruction: The Experimental Side of Digital Forensics
Directory of Open Access Journals (Sweden)
Fred Cohen
2013-12-01
Full Text Available Many in digital forensics seem to forget that the science part of digital forensics means experimentation and that implies a whole lot of things that most practitioners never learned.(see PDF for full column
Pulse amplitude and frequency effects in a pulsed packed column
Energy Technology Data Exchange (ETDEWEB)
Russell, S H
1954-04-15
A study has been made of the effect on the efficiency and capacity of applying pulses of varying amplitude and frequency to a packed column. In the efficiency studies, the maximum efficiency was obtained with a pulse having an amplitude of 3/8'' and a frequency of 140 cycles per minute. Under these conditions, the column was about five times as efficient as a simple packed column. Two general types of results were obtained in the capacity studies. Under certain conditions, the capacity increased over that of a simple packed column, but under others, it decreased. Some of the factors causing this were investigated but the fundamental reasons were not determined due to a lack of personnel for the necessary experiments. (author)