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Sample records for two-pass square channel

  1. Numerical simulations of heat transfer distribution of a two-pass square channel with V-rib turbulator and bleed holes

    Science.gov (United States)

    Kumar, Sourabh; Amano, R. S.; Lucci, Jose Martinez

    2013-08-01

    The blade tip region in gas turbine encounters high thermal loads due to temperature difference and hence efforts for high durability and safe operations are essential. Improved and robust methods of cooling are required to downgrade heat transfer rate to turbine blades. The blade tip regions, which are exposed to high gas flow, suffers high local thermal load which are due to external tip leakage. Jet impingement, pin cooling etc. are techniques used for cooling blades. A more usual way is to use serpentine passage with 180-degree turn. In this study, numerical simulation of heat transfer distribution of a two-pass square channel with rib turbulators and bleed holes were done. Periodical rib turbulators and bleed holes were used in the channel. The ribs arrangement were 60 degree V rib, 60 degree inverted V ribs, combination of 60 degree V rib at inlet and 60 inverted V rib at outlet section and combination of Inverted V at inlet and V rib at the outlet. The results were numerically computed using Fluent with Reynolds number of 12,500 and 28,500. Turbulence models used for computations were k-ω-SST and RSM. Temperature based and shear stress based techniques were used for heat transfer distribution prediction. The results for 60 degree V rib, 60 degree inverted V ribs were compared with the experimental results for validation of the results obtained. Detailed distribution shows distinctive peaks in heat transfer around bleed holes and rib turbulator. Comparisons of the overall performance of the models with different orientation of rib turbulator are presented. It is found that due to the combination of 60 degree inverted V rib in inlet and 60 V rib in outlet with bleed holes provides better heat treatment. It is suggested that the use of rib turbulator with bleed holes provides suitable for augmenting blade cooling to achieve an optimal balance between thermal and mechanical design requirements.

  2. Numerical Simulation of Turbulent Fluid Flow and Heat Transfer in a Ribbed Rotating Two-Pass Square Duct

    Directory of Open Access Journals (Sweden)

    Liou Tong-Miin

    2005-01-01

    Full Text Available The local turbulent fluid flow and heat transfer in a rotating two-pass square duct with 19 pairs of in-line 90 ∘ ribs have been investigated computationally. A Reynolds-averaged Navier-Stokes equation (RANS with a two-layer k − ϵ turbulence model was solved. The in-line 90 ∘ ribs were arranged on the leading and trailing walls with rib height-to-hydraulic diameter ratio and pitch-to-height ratio of 0.136 and 10, respectively. The Reynolds number, based on duct hydraulic diameter and bulk mean velocity, was fixed at 1.0 × 10 4 whereas the rotational number varied from 0 to 0.2 . Results are validated with previous measured velocity field and heat transfer coefficient distributions. The validation shows that the effect of rotation on the passage-averaged Nusselt number ratio can be predicted reasonably well; nevertheless, the transverse mean velocity and, in turn, the distribution of regional-averaged Nusselt number ratio are markedly underpredicted in the regions toward which the Coriolis force is directed. Further CFD studies are needed.

  3. Local heat/mass transfer distributions around sharp 180 deg turns in two-pass smooth and rib-roughened channels

    Science.gov (United States)

    Han, J. C.; Chandra, P. R.; Lau, S. C.

    1988-01-01

    The napthalene sublimation technique was employed to study the detailed mass transfer distributions around the sharp 180 deg turns in a two-pass, square, smooth channel and in an identical channel with two rib-roughened opposite walls. Experiments conducted for Reynolds numbers of 15,000, 30,000, and 60,000 indicate that the Sherwood numbers on the top, outer, and inner walls around the turn in the rib-roughened channel are higher than the corresponding Sherwood numbers around the turn in the smooth channel. Sherwood numbers after the sharp turn are found to be higher than those before the turn for both the smooth and the ribbed channels.

  4. Heat transfer in a two-pass internally ribbed turbine blade coolant channel with cylindrical vortex generators

    Energy Technology Data Exchange (ETDEWEB)

    Hibbs, R.; Chen, Y.; Nikitopoulos, D. [Louisiana State Univ., Baton Rouge, LA (United States)] [and others

    1995-10-01

    The effect of vortex generators on the mass (heat) transfer from the ribbed passage of a two pass turbine blade coolant channel is investigated with the intent of optimizing the vortex generator geometry so that significant enhancements in mass/heat transfer can be achieved. In the experimental configuration considered, ribs are mounted on two opposite walls; all four walls along each pass are active and have mass transfer from their surfaces but the ribs are non-participating. Mass transfer measurements, in the form of Sherwood number ratios, are made along the centerline and in selected inter-rib modules. Results are presented for Reynolds number in the range of 5,000 to 40,000, pitch to rib height ratios of 10.5 and 21, and vortex generator-rib spacing to rib height ratios of 0.55, and 1.5. Centerline and spanwise averaged Sherwood number ratios are presented along with contours of the Sherwood number ratios. Results indicate that the vortex generators induce substantial increases in the local mass transfer rates, particularly along the side walls, and modest increases in the average mass transfer rates. The vortex generators have the effect of making the inter-rib profiles along the ribbed walls more uniform. Along the side walls, horse-shoe vortices that characterize the vortex generator wake are associated with significant mass transfer enhancements. The wake effects and the levels of enhancement decrease somewhat with increasing Reynolds number and decreasing pitch.

  5. Numerical Study of the Rib Arrangements for Enhancing Heat Transfer in a Two-pass Channel of Large Aspect Ratio

    Energy Technology Data Exchange (ETDEWEB)

    Han, Sol; Choi, Seok Min; Sohn, Ho-Seong; Cho, Hyung Hee [Yonsei Univ., Seoul (Korea, Republic of)

    2017-03-15

    The present study investigated the effect of the rib arrangement and a guide vane for enhancing internal cooling of the blade. Two types of rib arrangements were used in the first and second passage in parallel. Aspect ratio of the channel was 5 and a fixed Reynolds number based on hydraulic diameter was 10,000. The attack angle of rib was 60°, rib pitch-to-height ratio (p/e) was 10, and the rib height-to-hydraulic-diameter ratio (e/D{sub n}) was 0.075. The effect of an interaction between Dean vortices and the secondary vortices from the first passage was observed. Overall, the attack angle of rib in the first passage was dominant factor to heat transfer and flow patterns in turning region. Also, the channel with a guide vane showed enhanced heat transfer at the tip surface with reducing flow separation and recirculation.

  6. Square root approximation to the poisson channel

    NARCIS (Netherlands)

    Tsiatmas, A.; Willems, F.M.J.; Baggen, C.P.M.J.

    2013-01-01

    Starting from the Poisson model we present a channel model for optical communications, called the Square Root (SR) Channel, in which the noise is additive Gaussian with constant variance. Initially, we prove that for large peak or average power, the transmission rate of a Poisson Channel when coding

  7. Decision-Directed Recursive Least Squares MIMO Channels Tracking

    Directory of Open Access Journals (Sweden)

    Karami Ebrahim

    2006-01-01

    Full Text Available A new approach for joint data estimation and channel tracking for multiple-input multiple-output (MIMO channels is proposed based on the decision-directed recursive least squares (DD-RLS algorithm. RLS algorithm is commonly used for equalization and its application in channel estimation is a novel idea. In this paper, after defining the weighted least squares cost function it is minimized and eventually the RLS MIMO channel estimation algorithm is derived. The proposed algorithm combined with the decision-directed algorithm (DDA is then extended for the blind mode operation. From the computational complexity point of view being versus the number of transmitter and receiver antennas, the proposed algorithm is very efficient. Through various simulations, the mean square error (MSE of the tracking of the proposed algorithm for different joint detection algorithms is compared with Kalman filtering approach which is one of the most well-known channel tracking algorithms. It is shown that the performance of the proposed algorithm is very close to Kalman estimator and that in the blind mode operation it presents a better performance with much lower complexity irrespective of the need to know the channel model.

  8. Motion of an elastic capsule in a square microfluidic channel.

    Science.gov (United States)

    Kuriakose, S; Dimitrakopoulos, P

    2011-07-01

    In the present study we investigate computationally the steady-state motion of an elastic capsule along the centerline of a square microfluidic channel and compare it with that in a cylindrical tube. In particular, we consider a slightly over-inflated elastic capsule made of a strain-hardening membrane with comparable shearing and area-dilatation resistance. Under the conditions studied in this paper (i.e., small, moderate, and large capsules at low and moderate flow rates), the capsule motion in a square channel is similar to and thus governed by the same scaling laws with the capsule motion in a cylindrical tube, even though in the channel the cross section in the upstream portion of large capsules is nonaxisymmetric (i.e., square-like with rounded corners). When the hydrodynamic forces on the membrane increase, the capsule develops a pointed downstream edge and a flattened rear (possibly with a negative curvature) so that the restoring tension forces are increased as also happens with droplets. Membrane tensions increase significantly with the capsule size while the area near the downstream tip is the most probable to rupture when a capsule flows in a microchannel. Because the membrane tensions increase with the interfacial deformation, a suitable Landau-Levich-Derjaguin-Bretherton analysis reveals that the lubrication film thickness h for large capsules depends on both the capillary number Ca and the capsule size a; our computations determine the latter dependence to be (in dimensionless form) h ~ a(-2) for the large capsules studied in this work. For small and moderate capsule sizes a, the capsule velocity Ux and additional pressure drop ΔP+ are governed by the same scaling laws as for high-viscosity droplets. The velocity and additional pressure drop of large thick capsules also follow the dynamics of high-viscosity droplets, and are affected by the lubrication film thickness. The motion of our large thick capsules is characterized by a Ux-U ~ h ~ a(-2

  9. Doppler-shift estimation of flat underwater channel using data-aided least-square approach

    Directory of Open Access Journals (Sweden)

    Weiqiang Pan

    2015-03-01

    Full Text Available In this paper we proposed a dada-aided Doppler estimation method for underwater acoustic communication. The training sequence is non-dedicate, hence it can be designed for Doppler estimation as well as channel equalization. We assume the channel has been equalized and consider only flat-fading channel. First, based on the training symbols the theoretical received sequence is composed. Next the least square principle is applied to build the objective function, which minimizes the error between the composed and the actual received signal. Then an iterative approach is applied to solve the least square problem. The proposed approach involves an outer loop and inner loop, which resolve the channel gain and Doppler coefficient, respectively. The theoretical performance bound, i.e. the Cramer-Rao Lower Bound (CRLB of estimation is also derived. Computer simulations results show that the proposed algorithm achieves the CRLB in medium to high SNR cases.

  10. Doppler-shift estimation of flat underwater channel using data-aided least-square approach

    Science.gov (United States)

    Pan, Weiqiang; Liu, Ping; Chen, Fangjiong; Ji, Fei; Feng, Jing

    2015-06-01

    In this paper we proposed a dada-aided Doppler estimation method for underwater acoustic communication. The training sequence is non-dedicate, hence it can be designed for Doppler estimation as well as channel equalization. We assume the channel has been equalized and consider only flat-fading channel. First, based on the training symbols the theoretical received sequence is composed. Next the least square principle is applied to build the objective function, which minimizes the error between the composed and the actual received signal. Then an iterative approach is applied to solve the least square problem. The proposed approach involves an outer loop and inner loop, which resolve the channel gain and Doppler coefficient, respectively. The theoretical performance bound, i.e. the Cramer-Rao Lower Bound (CRLB) of estimation is also derived. Computer simulations results show that the proposed algorithm achieves the CRLB in medium to high SNR cases.

  11. Sand transport in a two pass internal cooling duct with rib turbulators

    International Nuclear Information System (INIS)

    Singh, Sukhjinder; Tafti, Danesh; Reagle, Colin; Delimont, Jacob; Ng, Wing; Ekkad, Srinath

    2014-01-01

    Highlights: • Highest particle impingement observed in the bend and first quarter of 2nd pass. • Average particle impingement per pitch is 28% higher in the second pass. • Rib faces are by far the most susceptible to particle impingement. • Particle impingement is sensitive to particle size. • Particle impingement is sensitive to wall collision model used. - Abstract: Jet engines often operate under dirty conditions where large amounts of particulate matter can be ingested, especially, sand, ash and dirt. Particulate matter in different engine components can lead to degradation in performance. The focus of this study is to investigate the sand transport and deposition in the internal cooling passages of turbine blades. A two pass stationary square duct with rib turbulators subjected to sand ingestion is studied using Large Eddy Simulations (LES). Each pass has ribs on two opposite walls and aligned normal to the main flow direction. The rib pitch to rib height (P/e) is 9.28, the rib height to channel hydraulic diameter (e/D h ) is 0.0625 and calculations have been carried out for a bulk Reynolds number of 25,000. Particle sizes in the range 0.5–25 μm are considered, with the same size distribution as found in Arizona Road Dust (medium). Large Eddy Simulation (LES) with a wall-model is used to model the flow and sand particles are modeled using a discrete Lagrangian framework. Results quantify the distribution of particle impingement density on all surfaces. Highest particle impingement density is found in the first quarter section of the second pass after the 180° turn, where the recorded impingement is more than twice that of any other region. It is also found that the average particle impingement per pitch is 28% higher in the second pass than the first pass. Results show lower particle tendency to impact the region immediately behind the rib in the first pass compared to the second pass where particle impingement is more uniform in the region

  12. Forced convection heat transfer of steam in a square ribbed channel

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jiazeng; Gao, Jianmin; Gao, Tieyu [Xi' an Jiaotong University, Shaanxi (China)

    2012-04-15

    An experimental study of heat transfer characteristics of steam in a square channel (simulating a gas turbine blade cooling passage) with two opposite surfaces roughened by 60 deg parallel ribs was performed. The ranges of key governing parameters were: Reynolds numbers (Re) based on the channel hydraulic diameter (30000-140000), entry gauge pressure (0.2Mpa-0.5Mpa), heat flux of heat transfer surface area (5kWm{sup -2}-20kWm{sup -2}), and steam superheat (13 .deg. C-51 .deg. C). The test channel length was 1000mm, while the rib spacing (p/e) was 10, and the ratio of rib height (e) to hydraulic diameter (D) was 0.048. The test channel was heated by passing current through stainless steel walls instrumented with thermocouples. The local heat transfer coefficients on the ribbed wall from the channel entrance to the fully developed regions were measured. The semi-empirical correlation was fitted out by using the average Nusselt numbers in the fully developed region to cover the range of Reynolds number. The correlation can be used in the design of new generation of gas turbine blade cooled by steam.

  13. CFD Analysis of Square Flow Channel in Thermal Engine Rocket Adventurer for Space Nuclear Application

    International Nuclear Information System (INIS)

    Nam, S. H.; Suh, K. Y.; Kang, S. G.

    2008-01-01

    Solar system exploration relying on chemical rockets suffers from long trip time and high cost. In this regard nuclear propulsion is an attractive option for space exploration. The performance of Nuclear Thermal Rocket (NTR) is more than twice that of the best chemical rocket. Resorting to the pure hydrogen (H 2 ) propellant the NTRs can possibly achieve as high as 1,000 s of specific impulse (I sp ) representing the ratio of the thrust over the fuel consumption rate, as compared to only 425 s of H 2 /O 2 rockets. If we reflect on the mission to Mars, NTRs would reduce the round trip time to less than 300 days, instead of over 600 days with chemical rockets. This work presents CFD analysis of one Fuel Element (FE) of Thermal Engine Rocket Adventurer (TERA). In particular, one Square Flow Channel (SFC) is analyzed in Square Lattice Honeycomb (SLHC) fuel to examine the effects of mass flow rate on rocket performance

  14. Tuberlent heat transfer and friction in four-wall convergent/divergent square channels with one ribbed wall

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Soo Whan; Lee, Myung Sung [Dept. of Mechanical System Engineering, Institute of Marine Industry, Gyeongsang National University, Jinju (Korea, Republic of)

    2015-10-15

    The local heat transfer and pressure drop of developed turbulent flows in convergent/divergent channels with square axial cross-sectional areas were experimentally investigated to improve the channel design, such as a gas turbine cooling system. Square convergent/divergent channels with one ribbed wall were manufactured with a fixed rib height e of 10 mm and a ratio of rib spacing p to height e of 10. The measurement was conducted for Reynolds numbers from 15,000 to 89,000. Convergent, divergent, and straight channels with ratios D{sub ho}/D{sub hi} of 0.75, 1.33, and 1.0, respectively, are considered. Of the three channel types, the ribbed divergent channel was found to produce the best thermal performance under identical flow rate, pumping power, and pressure loss conditions.

  15. CFD Analysis of Square Flow Channel in Thermal Engine Rocket Adventurer for Space Nuclear Application

    Energy Technology Data Exchange (ETDEWEB)

    Nam, S. H.; Suh, K. Y. [Seoul National University, Seoul (Korea, Republic of); Kang, S. G. [PHILOSOPHIA, Inc., Seoul (Korea, Republic of)

    2008-10-15

    Solar system exploration relying on chemical rockets suffers from long trip time and high cost. In this regard nuclear propulsion is an attractive option for space exploration. The performance of Nuclear Thermal Rocket (NTR) is more than twice that of the best chemical rocket. Resorting to the pure hydrogen (H{sub 2}) propellant the NTRs can possibly achieve as high as 1,000 s of specific impulse (I{sub sp}) representing the ratio of the thrust over the fuel consumption rate, as compared to only 425 s of H{sub 2}/O{sub 2} rockets. If we reflect on the mission to Mars, NTRs would reduce the round trip time to less than 300 days, instead of over 600 days with chemical rockets. This work presents CFD analysis of one Fuel Element (FE) of Thermal Engine Rocket Adventurer (TERA). In particular, one Square Flow Channel (SFC) is analyzed in Square Lattice Honeycomb (SLHC) fuel to examine the effects of mass flow rate on rocket performance.

  16. Jet pairing algorithm for the 6-jet Higgs channel via energy chi-square criterion

    International Nuclear Information System (INIS)

    Magallanes, J.B.; Arogancia, D.C.; Gooc, H.C.; Vicente, I.C.M.; Bacala, A.M.; Miyamoto, A.; Fujii, K.

    2002-01-01

    Study and discovery of the Higgs bosons at JLC (Joint Linear Collider) is one of the tasks of ACFA (Asian Committee for future Accelerators)-JLC Group. The mode of Higgs production at JLC is e + e - → Z 0 H 0 . In this paper, studies are concentrated on the Higgsstrahlung process and the selection of its signals by getting the right jet-pairing algorithm of 6-jet final state at 300 GeV assuming that Higgs boson mass is 120 GeV and luminosity is 500 fb -1 . The total decay width Γ (H 0 → all) and the efficiency of the signals at the JLC are studied utilizing the 6-jet channel. Out of the 91,500 Higgsstrahlung events, 4,174 6-jet events are selected. PYTHIA Monte Carlo Generator generates the 6-jet Higgsstrahlung channel according to the Standard Model. The generated events are then simulated by Quick Simulator using the JCL parameters. After tagging all 6 quarks which correspond to the 6-jet final state of the Higgsstrahlung, the mean energy of the Z, H, and W's are obtained. Having calculated these information, the event energy chi-square is defined and it is found that the correct combination have generally smaller value. This criterion can be used to find correct jet-pairing algorithm and as one of the cuts for the background signals later on. Other chi-definitions are also proposed. (S. Funahashi)

  17. Study of two-phase flow redistribution between two passes of a heat exchanger

    International Nuclear Information System (INIS)

    Mendes de Moura, L.F.

    1989-04-01

    The object of the present thesis deals with the study of two-phase flow redistribution between two passes of a heat exchanger. Mass flow rate measurements of each component performed at each channel outlet of the second pass allowed us to determine the influence of mass flow, gas quality, flow direction (upward or downward) and common header geometry upon flow redistribution. Local void fraction inside common header was measured with an optical probe. A two-dimensional two-phase flow computational code was developed from a two-fluid model. Modelling of interfacial momentum transfer was used in order to take into account twp-phase flow patterns in common headers. Numerical simulation results show qualitative agreement with experimental results. Present theoretical model limitations are analysed and future improvements are proposed [fr

  18. Mixed convection heat transfer from confined tandem square cylinders in a horizontal channel

    KAUST Repository

    Huang, Zhu

    2013-11-01

    This paper presents a numerical study on the two-dimensional laminar mixed convective flow and heat transfer around two identical isothermal square cylinders arranged in tandem and confined in a channel. The spacing between the cylinders is fixed with four widths of the cylinder and the blockage ratio and the Prandtl number are fixed at 0.1 and 0.7 respectively. The mixed convective flow and heat transfer is simulated by high accuracy multidomain pseudospectral method. The Reynolds number (Re) is studied in the range 80 ≤ Re ≤ 150, the Richardson number (Ri) demonstrating the influence of thermal buoyancy ranges from 0 to 1. Numerical results reveal that, with the thermal buoyancy effect, the mixed convective flow sheds vortex behind the cylinders and keeps periodic oscillating. The variations of characteristic quantities related to flow and heat transfer processes, such as the overall drag and lift coefficients and the Nusselt numbers, are presented and discussed. Furthermore, the influence of thermal buoyancy on the fluid flow and heat transfer are discussed and analysed. © 2013 Elsevier Ltd. All rights reserved.

  19. Wall-cooling-induced mixed-convection flow recirculation in a vertical square-array multi-rod channel

    International Nuclear Information System (INIS)

    Luangdilok, W.; Todreas, N.E.

    1989-01-01

    This work investigated the structure of penetrative flow recirculation and associated flow conditions in a multi-rod channel induced by interassembly heat transfer that causes cooling through channel walls. Three investigation approaches, experimental, numerical, and analytical were employed in a complimentary fashion. Physical experiments involved water flow visualization and temperature measurement in a 4x4 rod square channel. Numerical experiments involved 3-dimensional simulations of water and sodium flow in a 2x2-rod channels. An approximate reverse flow model including Prandtl number effect was developed. A correlating equation based on the model and experiments was verified for water to correctly predict the trend of the 4x4-rod experimental penetration depth data. (orig.)

  20. Performance monitoring of zircaloy-4 square fuel channels at TAPS-1 and 2

    International Nuclear Information System (INIS)

    Akhtar, J.; Ramu, A.; Anilkumar, K.R.; Sharma, B.L.; Bhattacharjee, S.; Ramamurty, U.; Srivastava, S.P.; Prasad, P.N.; Anantharaman, K.

    2006-01-01

    Tarapur Atomic Power Station is a twin unit Boiling Water Reactors. The initial rated capacity of each unit was 210 MWe. Subsequently due to Secondary Steam Generator tube leak problem, the units were de-rated to 160 MWe in the year 1984-85. The station has completed 36 years of successful commercial operation. TAPS reactor fuel channels are made of Zircaloy-4, material. These are used along with 6x6 array nuclear fuel assemblies. The fuel channels need to be discharged once it reaches an optimum exposure limit and based on the surveillance programme, which monitors the channels performance. NFC has indigenously developed fuel channels for TAPS and these are at various stages of exposure in both the reactor cores. The performance review of these channels was carried out by the experts from TAPS-Site, NPCIL-ED and RED, BARC. The two major factors, which affect fuel channels performance, are (a) Bulge and (b) Bow. The phenomenon of longitudinal bow occurs due to the neutron flux gradient across the channels faces. Studies made on this subject by General Electric (GE) indicated that this channel deflection occurs at a slow rate. Therefore, fuel channels surveillance programme is essential to check the irradiated fuel channels performance in order to replace the fuel channels once it reaches the optimum exposure limit. To estimate the useful life of irradiated fuel channels, channel deflection/bulge measurement inspection system and methodology was developed jointly by TAPS and Centre for Design and manufacture (CDM), BARC. This system was successfully deployed at TAPS. This paper briefly describes the developmental efforts made by Nuclear Fuel Complex (NFC), Hyderabad, NPCIL-Fuel Group, Engg.Directorate, RED/BARC, CDM/BARC. (author)

  1. Numerical prediction of turbulent heat transfer augmentation in an annular fuel channel with two-dimensional square ribs

    International Nuclear Information System (INIS)

    Takase, Kazuyuki

    1996-01-01

    The square-ribbed fuel rod for high temperature gas-cooled reactors was developed in order to enhance the turbulent heat transfer in comparison with the standard fuel rod. To evaluate the heat transfer performance of the square-ribbed fuel rod, the turbulent heat transfer coefficients in an annular fuel channel with repeated two-dimensional square ribs were analyzed numerically on a fully developed incompressible flow using the k - ε turbulence model and the two-dimensional axisymmetrical coordinate system. Numerical analyses were carried out for a range of Reynolds numbers from 3000 to 20000 and ratios of square-rib pitch to height of 10, 20 and 40, respectively. The predicted values of the heat transfer coefficients agreed within an error of 10% for the square-rib pitch to height ratio of 10, 20% for 20 and 25% for 40, respectively, with the heat transfer empirical correlations obtained from the experimental data. It was concluded by the present study that the effect of the heat transfer augmentation by square ribs could be predicted sufficiently by the present numerical simulations and also a part of its mechanism could be explained by means of the change in the turbulence kinematic energy distribution along the flow direction. (author)

  2. Numerical prediction of augmented turbulent heat transfer in an annular fuel channel with repeated two-dimensional square ribs

    International Nuclear Information System (INIS)

    Takase, K.

    1996-01-01

    The square-ribbed fuel rod for high temperature gas-cooled reactors was designed and developed so as to enhance the turbulent heat transfer in comparison with the previous standard fuel rod. The turbulent heat transfer characteristics in an annular fuel channel with repeated two-dimensional square ribs were analysed numerically on a fully developed incompressible flow using the k-ε turbulence model and the two-dimensional axisymmetrical coordinate system. Numerical analyses were carried out under the conditions of Reynolds numbers from 3000 to 20000 and ratios of square-rib pitch to height of 10, 20 and 40 respectively. The predictions of the heat transfer coefficients agreed well within an error of 10% for the square-rib pitch to height ratio of 10, 20% for 20 and 25% for 40 respectively, with the heat transfer empirical correlations obtained from the experimental data due to the simulated square-ribbed fuel rods. Therefore it was found that the effect of heat transfer augmentation due to the square ribs could be predicted by the present numerical simulations and the mechanism could be explained by the change in the turbulence kinematic energy distribution along the flow direction. (orig.)

  3. Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, M., E-mail: micheline.abbas@ensiacet.fr [Laboratoire de Génie Chimique, Université de Toulouse INPT-UPS, 31030, Toulouse (France); CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Magaud, P. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Gao, Y. [Institut Clément Ader, Université de Toulouse UPS-INSA-ISAE-Mines Albi, 31400, Toulouse (France); Geoffroy, S. [CNRS, Fédération de recherche FERMaT, CNRS, 31400, Toulouse (France); Laboratoire Matériaux et Durabilité des Constructions, Université de Toulouse (France); UPS, INSA, 31077, Toulouse (France)

    2014-12-15

    The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions.

  4. Migration of finite sized particles in a laminar square channel flow from low to high Reynolds numbers

    International Nuclear Information System (INIS)

    Abbas, M.; Magaud, P.; Gao, Y.; Geoffroy, S.

    2014-01-01

    The migration of neutrally buoyant finite sized particles in a Newtonian square channel flow is investigated in the limit of very low solid volumetric concentration, within a wide range of channel Reynolds numbers Re = [0.07-120]. In situ microscope measurements of particle distributions, taken far from the channel inlet (at a distance several thousand times the channel height), revealed that particles are preferentially located near the channel walls at Re > 10 and near the channel center at Re < 1. Whereas the cross-streamline particle motion is governed by inertia-induced lift forces at high inertia, it seems to be controlled by shear-induced particle interactions at low (but finite) Reynolds numbers, despite the low solid volume fraction (<1%). The transition between both regimes is observed in the range Re = [1-10]. In order to exclude the effect of multi-body interactions, the trajectories of single freely moving particles are calculated thanks to numerical simulations based on the force coupling method. With the deployed numerical tool, the complete particle trajectories are accessible within a reasonable computational time only in the inertial regime (Re > 10). In this regime, we show that (i) the particle undergoes cross-streamline migration followed by a cross-lateral migration (parallel to the wall) in agreement with previous observations, and (ii) the stable equilibrium positions are located at the midline of the channel faces while the diagonal equilibrium positions are unstable. At low flow inertia, the first instants of the numerical simulations (carried at Re = O(1)) reveal that the cross-streamline migration of a single particle is oriented towards the channel wall, suggesting that the particle preferential positions around the channel center, observed in the experiments, are rather due to multi-body interactions

  5. The thermal performance of the two-pass, two-glass-cover solar air heater

    Energy Technology Data Exchange (ETDEWEB)

    Persad, P.; Sateunanathan, S.

    1983-08-01

    Analytic models are developed for the performance prediction of a two-glass-cover solar air heater operated in both the single-pass and two-pass modes. It is shown that the two-pass mode of operation is superior to the single-pass mode of operation over the range of collector inlet temperatures considered. This is seen to be mainly due to the fact that, in the two-pass mode of operation, the outer glass cover is cooled by the working fluid, thereby reducing the top losses. It is also shown that the performance in the two-pass mode of operation is independent of length, over the range of collector lengths considered, and that a critical plate spacing, dependent on the temperature level of operation of the collector, is indicated. Predicted values of performance are in good agreement with experimental results.

  6. Exact Symbol Error Probability of Square M-QAM Signaling over Generalized Fading Channels subject to Additive Generalized Gaussian Noise

    KAUST Repository

    Soury, Hamza

    2013-07-01

    This paper considers the average symbol error probability of square Quadrature Amplitude Modulation (QAM) coherent signaling over flat fading channels subject to additive generalized Gaussian noise. More specifically, a generic closedform expression in terms of the Fox H function and the bivariate Fox H function is offered for the extended generalized-K fading case. Simplifications for some special fading distributions such as generalized-K fading, Nakagami-m fading, and Rayleigh fading and special additive noise distributions such as Gaussian and Laplacian noise are then presented. Finally, the mathematical formalism is illustrated by some numerical examples verified by computer based simulations for a variety of fading and additive noise parameters.

  7. Range resolution improvement in passive bistatic radars using nested FM channels and least squares approach

    Science.gov (United States)

    Arslan, Musa T.; Tofighi, Mohammad; Sevimli, Rasim A.; ćetin, Ahmet E.

    2015-05-01

    One of the main disadvantages of using commercial broadcasts in a Passive Bistatic Radar (PBR) system is the range resolution. Using multiple broadcast channels to improve the radar performance is offered as a solution to this problem. However, it suffers from detection performance due to the side-lobes that matched filter creates for using multiple channels. In this article, we introduce a deconvolution algorithm to suppress the side-lobes. The two-dimensional matched filter output of a PBR is further analyzed as a deconvolution problem. The deconvolution algorithm is based on making successive projections onto the hyperplanes representing the time delay of a target. Resulting iterative deconvolution algorithm is globally convergent because all constraint sets are closed and convex. Simulation results in an FM based PBR system are presented.

  8. Pulse propagation in a two-pass optical amplifier with arbitrary laser beams overlap

    Directory of Open Access Journals (Sweden)

    AH Farahbod

    2011-09-01

    Full Text Available An analytical model for two-pass optical amplifier with arbitrary beams overlap has been developed which generalized the classical theory of Frantz-Nodvik for single pass amplifier. The effect of counterpropagating beams on gain and output energy fluence included in the model. Moreover, the appropriate limiting relations for two special cases of weak input signal and saturation state of the amplifier gain have been derived. The results indicate that for complete beams overlap, the gain and output energy have the least values. The model predictions are consistent with experimental observations and exact analytical model for two-pass amplifier when beam propagation paths are coincided.

  9. Speech overlap detection in a two-pass speaker diarization system

    NARCIS (Netherlands)

    Huijbregts, M.A.H.; Leeuwen, D.A. van; Jong, F. M. G de

    2009-01-01

    In this paper we present the two-pass speaker diarization system that we developed for the NIST RT09s evaluation. In the first pass of our system a model for speech overlap detection is gen- erated automatically. This model is used in two ways to reduce the diarization errors due to overlapping

  10. Speech overlap detection in a two-pass speaker diarization system

    NARCIS (Netherlands)

    Huijbregts, M.; Leeuwen, D.A. van; Jong, F.M.G. de

    2009-01-01

    In this paper we present the two-pass speaker diarization system that we developed for the NIST RT09s evaluation. In the first pass of our system a model for speech overlap detection is generated automatically. This model is used in two ways to reduce the diarization errors due to overlapping

  11. Two-pass imputation algorithm for missing value estimation in gene expression time series.

    Science.gov (United States)

    Tsiporkova, Elena; Boeva, Veselka

    2007-10-01

    Gene expression microarray experiments frequently generate datasets with multiple values missing. However, most of the analysis, mining, and classification methods for gene expression data require a complete matrix of gene array values. Therefore, the accurate estimation of missing values in such datasets has been recognized as an important issue, and several imputation algorithms have already been proposed to the biological community. Most of these approaches, however, are not particularly suitable for time series expression profiles. In view of this, we propose a novel imputation algorithm, which is specially suited for the estimation of missing values in gene expression time series data. The algorithm utilizes Dynamic Time Warping (DTW) distance in order to measure the similarity between time expression profiles, and subsequently selects for each gene expression profile with missing values a dedicated set of candidate profiles for estimation. Three different DTW-based imputation (DTWimpute) algorithms have been considered: position-wise, neighborhood-wise, and two-pass imputation. These have initially been prototyped in Perl, and their accuracy has been evaluated on yeast expression time series data using several different parameter settings. The experiments have shown that the two-pass algorithm consistently outperforms, in particular for datasets with a higher level of missing entries, the neighborhood-wise and the position-wise algorithms. The performance of the two-pass DTWimpute algorithm has further been benchmarked against the weighted K-Nearest Neighbors algorithm, which is widely used in the biological community; the former algorithm has appeared superior to the latter one. Motivated by these findings, indicating clearly the added value of the DTW techniques for missing value estimation in time series data, we have built an optimized C++ implementation of the two-pass DTWimpute algorithm. The software also provides for a choice between three different

  12. Effect of Channel Orientation and Rib Pitch-to-Height Ratio on Pressure Drop in a Rotating Square Channel with Ribs on Two Opposite Surfaces

    Directory of Open Access Journals (Sweden)

    Prabhu S. V.

    2005-01-01

    Full Text Available The effect of channel orientation and rib pitch-to-height ratio on the pressure drop distribution in a rib-roughened channel is an important issue in turbine blade cooling. The present investigation is a study of the overall pressure drop distribution in a square cross-sectioned channel, with rib turbulators, rotating about an axis normal to the free stream. The ribs are configured in a symmetric arrangement on two opposite surfaces with a rib angle of 90 ∘ to the mainstream flow. The study has been conducted for three Reynolds numbers, namely, 13 000, 17 000, and 22 000 with the rotation number varying from 0– 0.38 . Experiments have been carried out for various rib pitch-to-height ratios ( P/e with a constant rib height-to-hydraulic diameter ratio ( e/D of 0.1 . The test section in which the ribs are placed on the leading and trailing surfaces is considered as the base case ( orientation angle= 0 ∘ , Coriolis force vector normal to the ribbed surfaces. The channel is turned about its axis in steps of 15 ∘ to vary the orientation angle from 0 ∘ to 90 ∘ . The overall pressure drop does not change considerably under conditions of rotation for the base case. However, for the other cases tested, it is observed that the overall pressure drop increases with an increase in the rotation number for a given orientation angle and also increases with an increase in the orientation angle for a given rotation number. This change is attributed to the variation in the separation zone downstream of the ribs due to the presence of the Coriolis force—local pressure drop data is presented which supports this idea. At an orientation angle of 90 ∘ (ribs on the top and bottom surfaces, Coriolis force vector normal to the smooth surfaces, the overall pressure drop is observed to be maximum during rotation. The overall pressure drop for a case with a rib pitch-to-height ratio of 5 on both surfaces is found to be the highest

  13. Evaluation of Two Passes Cold Pilgering Property for PLUS7TM Guide Thimble and Instrumentation Tubing

    Energy Technology Data Exchange (ETDEWEB)

    Park, Min Young; Park, Ki Bum; Kim, In Kyu; Lee, Young Hee; Kahng, Jong Yeol [KEPCO Nuclear Fuel Co., Daejeon (Korea, Republic of)

    2015-05-15

    The thermo-mechanical property of zirconium alloy tube is well known to be influenced by pilgering pass schedule and its tooling; thus the control of its microstructure and mechanical property in the final tube production stage for nuclear fuel applications is a major concern of tube manufacture. To fabricate final tube, the 3 passes pilgering is applied in general by using TREX(Tube Reduced EXtrusion), 63.5mm outer diameter(OD), in KEPCO NF and most of Zr tube manufacturing companies. They are also taking big efforts to reduce pilgering step for the sake of increasing the efficiency of production in the forming stage of tube. The objective of this study is to develop two passes of pilgering schedule from the conventional three passes of pilgering schedule for manufacturing the Guide Thimble and Instrumentation tube conforming to specification, which are newly developing component for the advanced nuclear fuel assembly in KEPCO NF. CSR, hydride orientation, and structural integrity are well conformed to the desired targets so it is expected that both die and mandrel were newly designed for the PLUS7TM guide thimble and instrumentation tube with higher Q factor for two passes of pilgering at 50LC and 25LC pilger machine, instead of three passes of pilgering, are able to be applicable to this design of fuel component. If developed two passes pilgering is applied to current manufacturing process, it would improve not only productivity but also yield rate by reducing 3 steps(pilgering, heat-treatment, pickiling and cleaning) of manufacturing process. But additional tests(including in-pile test) should be performed in order to evaluate integrity in reactor.

  14. Local Nusselt number enhancement during gas-liquid Taylor bubble flow in a square mini-channel: An experimental study

    International Nuclear Information System (INIS)

    Majumder, Abhik; Mehta, Balkrishna; Khandekar, Sameer

    2013-01-01

    Taylor bubble flow takes place when two immiscible fluids (liquid-liquid or gas-liquid) flow inside a tube of capillary dimensions within specific range of volume flow ratios. In the slug flows where gas and liquid are two different phases, liquid slugs are separated by elongated Taylor bubbles. This singular flow pattern is observed in many engineering mini-/micro-scale devices like pulsating heat pipes, gas-liquid-solid monolithic reactors, micro-two-phase heat exchangers, digital micro-fluidics, micro-scale mass transfer process, fuel cells, etc. The unique and complex flow characteristics require understanding on local, as well as global, spatio-temporal scales. In the present work, the axial stream-wise profile of the fluid and wall temperature for air-water (i) isolated single Taylor bubble and, (ii) a train of Taylor bubbles, in a horizontal square channel of size 3.3 mm x 3.3 mm x 350 mm, heated from the bottom (heated length = 175 mm), with the other three sides kept insulated, are reported at different gas volume flow ratios. The primary aim is to study the enhancement of heat transfer due to the Taylor bubble train flow, in comparison with thermally developing single-phase flows. Intrusion of a bubble in the liquid flow drastically changes the local temperature profiles. The axial distribution of time-averaged local Nusselt number (Nu z ) shows that Taylor bubble train regime increases the transport of heat up to 1.2-1.6 times more as compared with laminar single-phase liquid flow. In addition, for a given liquid flow Reynolds number, the heat transfer enhancement is a function of the geometrical parameters of the unit cell, i.e., the length of adjacent gas bubble and water plug. (authors)

  15. Computing symmetrical strength of N-grams: a two pass filtering approach in automatic classification of text documents.

    Science.gov (United States)

    Agnihotri, Deepak; Verma, Kesari; Tripathi, Priyanka

    2016-01-01

    The contiguous sequences of the terms (N-grams) in the documents are symmetrically distributed among different classes. The symmetrical distribution of the N-Grams raises uncertainty in the belongings of the N-Grams towards the class. In this paper, we focused on the selection of most discriminating N-Grams by reducing the effects of symmetrical distribution. In this context, a new text feature selection method named as the symmetrical strength of the N-Grams (SSNG) is proposed using a two pass filtering based feature selection (TPF) approach. Initially, in the first pass of the TPF, the SSNG method chooses various informative N-Grams from the entire extracted N-Grams of the corpus. Subsequently, in the second pass the well-known Chi Square (χ(2)) method is being used to select few most informative N-Grams. Further, to classify the documents the two standard classifiers Multinomial Naive Bayes and Linear Support Vector Machine have been applied on the ten standard text data sets. In most of the datasets, the experimental results state the performance and success rate of SSNG method using TPF approach is superior to the state-of-the-art methods viz. Mutual Information, Information Gain, Odds Ratio, Discriminating Feature Selection and χ(2).

  16. The numerical and experimental study of two passes power plant condenser

    Directory of Open Access Journals (Sweden)

    Rusowicz Artur

    2017-01-01

    Full Text Available The steam condenser is one of the most important element in whole power plant installation. Their proper design and operation makes a significant contribution to the efficiency of electricity production. The purpose of this article is to propose a two-dimensional mathematical model that allows modeling condenser work. In the model, the tube bundle is treated as a porous bed. The analysis has been subjected to a two passes power condenser with a capacity of 50 MW. The mathematical analysis was compared with the results of experimental studies. The average error between the model and the experiment for difference of cooling water temperatures was 5.15% and 11.60% for the first and second pass respectively. This allows to conclude that the proposed model is good enough to optimize future work of the condenser.

  17. Visualization of mcr mRNA in a methanogen by fluorescence in situ hybridization with an oligonucleotide probe and two-pass tyramide signal amplification (two-pass TSA-FISH).

    Science.gov (United States)

    Kubota, Kengo; Ohashi, Akiyoshi; Imachi, Hiroyuki; Harada, Hideki

    2006-09-01

    Two-pass tyramide signal amplification-fluorescence in situ hybridization (two-pass TSA-FISH) with a horseradish peroxidase (HRP)-labeled oligonucleotide probe was applied to detect prokaryotic mRNA. In this study, mRNA of a key enzyme for methanogenesis, methyl coenzyme M reductase (mcr), in Methanococcus vannielii was targeted. Applicability of mRNA-targeted probes to in situ hybridization was verified by Clone-FISH. It was observed that sensitivity of two-pass TSA-FISH was significantly higher than that of TSA-FISH, which was further increased by the addition of dextran sulphate in TSA working solution. Signals from two-pass TSA-FISH were more reliable compared to the weak, spotty signals yielded by TSA-FISH.

  18. The initial study on supercritical water flow and heat transfer in square rod bundle channel with mixing vane

    International Nuclear Information System (INIS)

    Zuo Guoping; Cao Can; Yu Tao

    2010-01-01

    Three-dimensional rectangular channel with the mixing wine in supercritical water reactor was studied in the paper using the FLUENT software. The mixing wing elevation influence on temperature distribution and flow field were studied in the model. The results showed the mixing wing caused fluid circumferential flow, making flow hot and cold fluids mixed and fluid temperature uniform distribution, effectively improved the fuel rod surface temperature distribution and reduced hot temperature. Among the four cases of mixing wing elevation of 15, 30, 45 and 50 angle, 30 angle is the best case in improving temperature distribution. (authors)

  19. Detection of single-copy functional genes in prokaryotic cells by two-pass TSA-FISH with polynucleotide probes.

    Science.gov (United States)

    Kawakami, Shuji; Hasegawa, Takuya; Imachi, Hiroyuki; Yamaguchi, Takashi; Harada, Hideki; Ohashi, Akiyoshi; Kubota, Kengo

    2012-02-01

    In situ detection of functional genes with single-cell resolution is currently of interest to microbiologists. Here, we developed a two-pass tyramide signal amplification (TSA)-fluorescence in situ hybridization (FISH) protocol with PCR-derived polynucleotide probes for the detection of single-copy genes in prokaryotic cells. The mcrA gene and the apsA gene in methanogens and sulfate-reducing bacteria, respectively, were targeted. The protocol showed bright fluorescence with a good signal-to-noise ratio and achieved a high efficiency of detection (>98%). The discrimination threshold was approximately 82-89% sequence identity. Microorganisms possessing the mcrA or apsA gene in anaerobic sludge samples were successfully detected by two-pass TSA-FISH with polynucleotide probes. The developed protocol is useful for identifying single microbial cells based on functional gene sequences. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Using Squares to Sum Squares

    Science.gov (United States)

    DeTemple, Duane

    2010-01-01

    Purely combinatorial proofs are given for the sum of squares formula, 1[superscript 2] + 2[superscript 2] + ... + n[superscript 2] = n(n + 1) (2n + 1) / 6, and the sum of sums of squares formula, 1[superscript 2] + (1[superscript 2] + 2[superscript 2]) + ... + (1[superscript 2] + 2[superscript 2] + ... + n[superscript 2]) = n(n + 1)[superscript 2]…

  1. Digital squares

    DEFF Research Database (Denmark)

    Forchhammer, Søren; Kim, Chul E

    1988-01-01

    Digital squares are defined and their geometric properties characterized. A linear time algorithm is presented that considers a convex digital region and determines whether or not it is a digital square. The algorithm also determines the range of the values of the parameter set of its preimages....... The analysis involves transforming the boundary of a digital region into parameter space of slope and y-intercept...

  2. Latin Squares

    Indian Academy of Sciences (India)

    Admin

    2012-09-07

    Sep 7, 2012 ... must first talk of permutations and Latin squares. A permutation of a finite set of objects is a linear arrange- ment of ... with a special element 1 ... Of course, this has .... tion method to disprove Euler's conjecture for infinitely.

  3. Creating Magic Squares.

    Science.gov (United States)

    Lyon, Betty Clayton

    1990-01-01

    One method of making magic squares using a prolongated square is illustrated. Discussed are third-order magic squares, fractional magic squares, fifth-order magic squares, decimal magic squares, and even magic squares. (CW)

  4. Democracy Squared

    DEFF Research Database (Denmark)

    Rose, Jeremy; Sæbø, Øystein

    2005-01-01

    On-line political communities, such as the Norwegian site Demokratitorget (Democracy Square), are often designed according to a set of un-reflected assumptions about the political interests of their potential members. In political science, democracy is not taken as given in this way, but can...... be represented by different models which characterize different relationships between politicians and the citizens they represent. This paper uses quantitative and qualitative content analysis to analyze the communication mediated by the Democracy Square discussion forum in the first ten months of its life......-Republican model. In the qualitative analysis the discourse is analysed as repeating genres – patterns in the communication form which also reflect the conflict of interest between citizens and politicians. Though the analysis gives insight into the nature of the discourse the site supports, little is known about...

  5. All SQUARE

    CERN Multimedia

    1972-01-01

    With the existing Systems for using the accelerated protons, it is possible to supply only one slow ejected beam (feeding the East Hall) and, at the same time, to have only a small percentage of the beam on an internal target (feeding the South Hall). The arrangement will be replaced by a new System called SQUARE (Semi- QUAdrupole Resonant Extraction) which will give greater flexibility in supplying the three areas.

  6. On a two-pass scheme without a faraday mirror for free-space relativistic quantum cryptography

    Energy Technology Data Exchange (ETDEWEB)

    Kravtsov, K. S.; Radchenko, I. V. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation); Korol' kov, A. V. [Academy of Cryptography (Russian Federation); Kulik, S. P., E-mail: sergei.kulik@gmail.com [Moscow State University (Russian Federation); Molotkov, S. N., E-mail: sergei.molotkov@gmail.com [Academy of Cryptography (Russian Federation)

    2013-05-15

    The stability of destructive interference independent of the input polarization and the state of a quantum communication channel in fiber optic systems used in quantum cryptography plays a principal role in providing the security of communicated keys. A novel optical scheme is proposed that can be used both in relativistic quantum cryptography for communicating keys in open space and for communicating them over fiber optic lines. The scheme ensures stability of destructive interference and admits simple automatic balancing of a fiber interferometer.

  7. On a two-pass scheme without a faraday mirror for free-space relativistic quantum cryptography

    International Nuclear Information System (INIS)

    Kravtsov, K. S.; Radchenko, I. V.; Korol’kov, A. V.; Kulik, S. P.; Molotkov, S. N.

    2013-01-01

    The stability of destructive interference independent of the input polarization and the state of a quantum communication channel in fiber optic systems used in quantum cryptography plays a principal role in providing the security of communicated keys. A novel optical scheme is proposed that can be used both in relativistic quantum cryptography for communicating keys in open space and for communicating them over fiber optic lines. The scheme ensures stability of destructive interference and admits simple automatic balancing of a fiber interferometer.

  8. Performance comparison of weighted sum-minimum mean square error and virtual signal-to-interference plus noise ratio algorithms in simulated and measured channels

    DEFF Research Database (Denmark)

    Rahimi, Maryam; Nielsen, Jesper Ødum; Pedersen, Troels

    2014-01-01

    A comparison in data achievement between two well-known algorithms with simulated and real measured data is presented. The algorithms maximise the data rate in cooperative base stations (BS) multiple-input-single-output scenario. Weighted sum-minimum mean square error algorithm could be used...... in multiple-input-multiple-output scenarios, but it has lower performance than virtual signal-to-interference plus noise ratio algorithm in theory and practice. A real measurement environment consisting of two BS and two users have been studied to evaluate the simulation results....

  9. Microstructural and mechanical behaviors of nano-SiC-reinforced AA7075-O FSW joints prepared through two passes

    Energy Technology Data Exchange (ETDEWEB)

    Bahrami, Mohsen, E-mail: Mohsen.bahrami@aut.ac.ir [Faculty of Mining and Materials Engineering, Amirkabir University of Technology (AUT), Hafez Aveenue, Tehran (Iran, Islamic Republic of); Farahmand Nikoo, Mohsen [Faculty of Mining and Materials Engineering, Amirkabir University of Technology (AUT), Hafez Aveenue, Tehran (Iran, Islamic Republic of); Besharati Givi, Mohammad Kazem [Department of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2015-02-25

    In this paper, a threaded tapered pin tool was employed to fabricate a 2-pass friction stir welded (FSWed) joint. To investigate the benefits of nano-sized SiC particles on microstructural and mechanical properties of the joint, the experiment was repeated while SiC particles had been inserted along the joint line. In another joint, a square pin tool was applied in the second pass to evaluate the effectiveness of switching pin geometry between passes on the aforementioned properties. Microstructural features including grain size, second phase particles and reinforcement distribution were examined via optical and scanning electron microscopy (SEM) techniques. In addition to satisfactory connections between SiC particles and the matrix, the most homogenous particles distribution was observed in the specimen FSWed with both pin tools. This observation was further supported by atomic force microscopy (AFM) examination. Additionally, the foregoing joint demonstrated the maximum tensile strength which was synonymous with its smallest grain size. During tensile testing, SiC-free joint and SiC-reinforced ones fractured from stir zone (SZ) and base metal, respectively. Moreover, SiC-free joint showed necking phenomenon. SEM results showed that the SiC-reinforced specimens possessed ductile fracture morphologies. On the other hand, SiC-free specimen showed a quasi-cleavage fracture mode confirming its moderate percent elongation. In the meantime, SiC-reinforced specimens exhibited superior hardness level to SiC-free specimen.

  10. Energy and exergy analysis of a two pass photovoltaic –thermal (PV/T) air heater

    Energy Technology Data Exchange (ETDEWEB)

    Srinivas, M.; Jayaraj, S. [Department of Mechanical Engineering, National Institute of Technology, Calicut-673601 (India)

    2013-07-01

    A double pass hybrid solar air (PV/T) heater with slats is designed and fabricated to study elaborately its thermal and electrical performance corresponding to the warm and humid environment. Air as a heat removing fluid is made to flow through upper and lower channels of the collector. The collector is designed in such way that the absorber plate is partially covered by solar cells. Thin metallic strips (called slats) are attached longitudinally at the bottom side of the absorber plate to improve the overall system performance (by increasing the cooling rate of the absorber plate). Thermal and electrical performances of the whole system at different cooling rates are presented. The exergy analysis of double pass hybrid solar air (PV/T) heater with slats has also been carried out. The instantaneous overall energy and overall exergy efficiency of the double pass hybrid (PV/T) solar air heater varies between 29 – 37 percent and 14-17 percent respectively. These obtained values are comparable with that of published results.

  11. Enhanced mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joint using two-pass friction stir processing with rapid cooling

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Nan, E-mail: xunan@hhu.edu.cn; Bao, Yefeng

    2016-02-08

    In this study, tungsten inert gas (TIG) welded AZ31 magnesium alloy joint was subjected to two-pass rapid cooling friction stir processing (RC-FSP). The main results show that, two-pass RC-FSP causes the significant dissolution of the coarse eutectic β-Mg{sub 17}Al{sub 12} phase into the magnesium matrix and the remarkable grain refinement in the stir zone. The low-hardness region which frequently located at heat-affected zone was eliminated. The stir zone showed ultrafine grains of 3.1 μm, and exhibited a good combination of ultrahigh tensile strength of 284 MPa and large elongation of 7.1%. This work provides an effective strategy to enhance the strength of TIG welded magnesium alloy joint without ductility loss.

  12. Enhanced mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joint using two-pass friction stir processing with rapid cooling

    International Nuclear Information System (INIS)

    Xu, Nan; Bao, Yefeng

    2016-01-01

    In this study, tungsten inert gas (TIG) welded AZ31 magnesium alloy joint was subjected to two-pass rapid cooling friction stir processing (RC-FSP). The main results show that, two-pass RC-FSP causes the significant dissolution of the coarse eutectic β-Mg_1_7Al_1_2 phase into the magnesium matrix and the remarkable grain refinement in the stir zone. The low-hardness region which frequently located at heat-affected zone was eliminated. The stir zone showed ultrafine grains of 3.1 μm, and exhibited a good combination of ultrahigh tensile strength of 284 MPa and large elongation of 7.1%. This work provides an effective strategy to enhance the strength of TIG welded magnesium alloy joint without ductility loss.

  13. Dissimilar joining of galvanized high-strength steel to aluminum alloy in a zero-gap lap joint configuration by two-pass laser welding

    International Nuclear Information System (INIS)

    Ma, Junjie; Harooni, Masoud; Carlson, Blair; Kovacevic, Radovan

    2014-01-01

    Highlights: • Defect-free two-pass laser partially penetrated lap joint of galvanized steel to aluminum was achieved. • The thickness of the Al-rich intermetallic compounds could be controlled by optimal parameters. • The dynamic behavior of the molten pool and keyhole were monitored by a high speed charge-coupled device camera. • The presence of zinc in the intermetallic compounds could improve the strength of the lap joints. - Abstract: A welding procedure based on using two-pass laser scans is introduced for dissimilar joining of overlapped galvanized high-strength dual-phase (DP) steel DP590 to aluminum alloy (AA) 6061 sheets. The first pass is based on a defocused laser spot that scans across the top of the two overlapped sheets and heats the zinc coating at the faying surface to be melted and partially vaporized, while the second pass is executed with a focused laser spot in order to perform the welding. Completely defect-free galvanized steel to aluminum lap joints were obtained by using this two-pass laser welding procedure. An on-line machine vision system was applied to monitor the keyhole dynamics during the laser welding process. An energy-dispersive X-ray spectroscopy (EDS) was carried out to determine the atomic percent of zinc, aluminum, and iron in the galvanized steel to aluminum lap joints. Mechanical testing and micro-hardness test were conducted to evaluate the mechanical properties of the galvanized steel to aluminum lap joints. The experimental results showed that the lap joint of galvanized steel to aluminum obtained by the two-pass laser welding approach had a higher failure value than those joints obtained when the zinc at the faying surface was mechanically removed under the same welding speed and laser power

  14. Two-pass dual-energy CT imaging for simultaneous detection, characterization, and volume measurement of urinary stones with excretory-phase CT urography alone. A phantom study

    International Nuclear Information System (INIS)

    Takahashi, Satoru; Niikawa, Hidekazu; Shikata, Atsushi; Murakami, Emi; Tsunoda, Hiroshi; Yoshioka, Toshiaki; Yamamoto, Hiroshi; Itoh, Toshihide; Tsujihata, Masao

    2013-01-01

    The purpose of this study was to evaluate if two-pass dual-energy CT imaging - id est (i.e.), simultaneous three-material and two-material decomposition analysis - can depict and characterize urinary stones in various concentrations of iodine solution in vitro. Twelve urinary stones were scanned with a dual-source CT scanner. First, each stone (in a saline-filled tube) underwent single- and dual-energy mode CT scans in order to measure the volume of the stone. Each stone was then placed in various concentrations of contrast medium and scanned in dual-energy mode to calculate its volume via three-material decomposition analysis. Two-pass dual-energy CT imaging analysis software for the Matlab environment, which was developed specifically to process simultaneous three-material and two-material decomposition, was applied to characterize and calculate the volume of each stone. Although the virtual non-contrast images from three-material decomposition analysis clearly visualized all of the stones in contrast medium with up to 80 mgI/mL, the volumes of the uric acid stones were overestimated. Two-pass dual-energy CT imaging was able to depict and characterize non-uric-acid stones in diluted contrast medium with up to 80 mgI/mL, whereas uric acid stones were correctly evaluated in diluted contrast medium with 40 mgI/mL or less. Two-pass dual-energy CT imaging is able to depict and characterize urinary stones in contrast medium. (author)

  15. Exergy Analysis of a Two-Pass Reverse Osmosis (RO Desalination Unit with and without an Energy Recovery Turbine (ERT and Pressure Exchanger (PX

    Directory of Open Access Journals (Sweden)

    Nuri M. Eshoul

    2015-07-01

    Full Text Available This paper presents an exergy analysis of an actual two-pass (RO desalination system with the seawater solution treated as a real mixture and not an ideal mixture. The actual 127 ton/h two pass RO desalination plant was modeled using IPSEpro software and validated against operating data. The results show that using the (ERT and (PX reduced the total power consumption of the SWRO desalination by about 30% and 50% respectively, whereas, the specific power consumption for the SWRO per m3 water decreased from 7.2 kW/m3 to 5.0 kW/m3 with (ERT and 3.6 kW/m3 with (PX. In addition, the exergy efficiency of the RO desalination improved by 49% with ERT and 77% with PX and exergy destruction was reduced by 40% for (ERT and 53% for (PX. The results also showed that, when the (ERT and (PX were not in use, accounted for 42% of the total exergy destruction. Whereas, when (ERT and (PX are in use, the rejected seawater account maximum is 0.64%. Moreover, the (PX involved the smallest area and highest minimum separation work.

  16. Rate-distortion analysis of dead-zone plus uniform threshold scalar quantization and its application--part II: two-pass VBR coding for H.264/AVC.

    Science.gov (United States)

    Sun, Jun; Duan, Yizhou; Li, Jiangtao; Liu, Jiaying; Guo, Zongming

    2013-01-01

    In the first part of this paper, we derive a source model describing the relationship between the rate, distortion, and quantization steps of the dead-zone plus uniform threshold scalar quantizers with nearly uniform reconstruction quantizers for generalized Gaussian distribution. This source model consists of rate-quantization, distortion-quantization (D-Q), and distortion-rate (D-R) models. In this part, we first rigorously confirm the accuracy of the proposed source model by comparing the calculated results with the coding data of JM 16.0. Efficient parameter estimation strategies are then developed to better employ this source model in our two-pass rate control method for H.264 variable bit rate coding. Based on our D-Q and D-R models, the proposed method is of high stability, low complexity and is easy to implement. Extensive experiments demonstrate that the proposed method achieves: 1) average peak signal-to-noise ratio variance of only 0.0658 dB, compared to 1.8758 dB of JM 16.0's method, with an average rate control error of 1.95% and 2) significant improvement in smoothing the video quality compared with the latest two-pass rate control method.

  17. The Versatile Magic Square.

    Science.gov (United States)

    Watson, Gale A.

    2003-01-01

    Demonstrates the transformations that are possible to construct a variety of magic squares, including modifications to challenge students from elementary grades through algebra. Presents an example of using magic squares with students who have special needs. (YDS)

  18. Partial update least-square adaptive filtering

    CERN Document Server

    Xie, Bei

    2014-01-01

    Adaptive filters play an important role in the fields related to digital signal processing and communication, such as system identification, noise cancellation, channel equalization, and beamforming. In practical applications, the computational complexity of an adaptive filter is an important consideration. The Least Mean Square (LMS) algorithm is widely used because of its low computational complexity (O(N)) and simplicity in implementation. The least squares algorithms, such as Recursive Least Squares (RLS), Conjugate Gradient (CG), and Euclidean Direction Search (EDS), can converge faster a

  19. Irrational Square Roots

    Science.gov (United States)

    Misiurewicz, Michal

    2013-01-01

    If students are presented the standard proof of irrationality of [square root]2, can they generalize it to a proof of the irrationality of "[square root]p", "p" a prime if, instead of considering divisibility by "p", they cling to the notions of even and odd used in the standard proof?

  20. Square through tube

    International Nuclear Information System (INIS)

    Akita, Junji; Honma, Toei.

    1975-01-01

    Object: To provide a square through tube involving thermal movement in pipelines such as water supply pump driving turbine exhaust pipe (square-shaped), which is wide in freedom with respect to shape and dimension thereof for efficient installation at site. Structure: In a through tube to be airtightly retained for purpose of decontamination in an atomic power plant, comprising a seal rubber plate, a band and a bolt and a nut for securing said plate, the seal rubber plate being worked into the desired shape so that it may be placed in intimate contact with the concrete floor surface by utilization of elasticity of rubber, thereby providing airtightness at a corner portion of the square tube. (Kamimura, M.)

  1. Two-pass greedy regular expression parsing

    DEFF Research Database (Denmark)

    Grathwohl, Niels Bjørn Bugge; Henglein, Fritz; Nielsen, Lasse

    2013-01-01

    We present new algorithms for producing greedy parses for regular expressions (REs) in a semi-streaming fashion. Our lean-log algorithm executes in time O(mn) for REs of size m and input strings of size n and outputs a compact bit-coded parse tree representation. It improves on previous algorithms...... by: operating in only 2 passes; using only O(m) words of random-access memory (independent of n); requiring only kn bits of sequentially written and read log storage, where k ... and not requiring it to be stored at all. Previous RE parsing algorithms do not scale linearly with input size, or require substantially more log storage and employ 3 passes where the first consists of reversing the input, or do not or are not known to produce a greedy parse. The performance of our unoptimized C...

  2. Measurement of the top anti-top quark pair production cross-section in the [tau] + jets channel at [square root of s] = 7 TeV using ATLAS detector

    Science.gov (United States)

    Rashid, Teeba

    Large Hadron Collider (LHC) is a top quark factory, which is the heaviest elementary particle discovered so far. Due to its small life-time top quark decays before hadronization, and hence most of its properties are not washed out. Top quark events are often a large background in many beyond the Standard Model scenarios. For this reason, a deep knowledge of its properties and behavior is of crucial importance in searches for new physics at the LHC. This dissertation describes a measurement of the top anti-top pair production cross-section in tau + jets channel. The measurement is obtained by using 4.7 fb-1 data collected in year 2011 by ATLAS detector from proton proton (pp) collisions at the center of mass energy s = 7 TeV. Selected events are required to have one isolated tau with missing transverse energy and hadronic jets, at least one of which must be originated from a b quark. The measured cross section is 152 +/- 12 (stat.) +28-30 (syst.); +/- 3(lumi.) pb, which is in agreement with standard model predictions.

  3. ELMO Bumpy Square proposal

    International Nuclear Information System (INIS)

    Dory, R.A.; Uckan, N.A.; Ard, W.B.

    1986-10-01

    The ELMO Bumpy Square (EBS) concept consists of four straight magnetic mirror arrays linked by four high-field corner coils. Extensive calculations show that this configuration offers major improvements over the ELMO Bumpy Torus (EBT) in particle confinement, heating, transport, ring production, and stability. The components of the EBT device at Oak Ridge National Laboratory can be reconfigured into a square arrangement having straight sides composed of EBT coils, with new microwave cavities and high-field corners designed and built for this application. The elimination of neoclassical convection, identified as the dominant mechanism for the limited confinement in EBT, will give the EBS device substantially improved confinement and the flexibility to explore the concepts that produce this improvement. The primary goals of the EBS program are twofold: first, to improve the physics of confinement in toroidal systems by developing the concepts of plasma stabilization using the effects of energetic electrons and confinement optimization using magnetic field shaping and electrostatic potential control to limit particle drift, and second, to develop bumpy toroid devices as attractive candidates for fusion reactors. This report presents a brief review of the physics analyses that support the EBS concept, discussions of the design and expected performance of the EBS device, a description of the EBS experimental program, and a review of the reactor potential of bumpy toroid configurations. Detailed information is presented in the appendices

  4. Search for 3rd Generation Vector Leptoquarks in the Di-tau Di-jet Channel in Proton Antiproton Collisions at square √s = 1.96 TeV

    Energy Technology Data Exchange (ETDEWEB)

    Forrester, Stanley Scott [Univ. of California, Davis, CA (United States)

    2006-01-01

    We search for third generation vector leptoquarks (V LQ3) produced in colliding p$\\bar{p}$ beams operating at √s = 1.96 TeV at the CDF experiment in Run II of the Fermilab Tevatron. We use 322 pb-1 of data to search for the V LQ3 signal in the di-tau plus di-jet channel. For the first time, the full matrix element is used in the Monte Carlo simulation of this signal. With no events observed in the signal region, we set a 95% C.L. upper limit on the V LQ3 pair production cross section of σ < 344fb, assuming Yang-Mills couplings and Br(V LQ3 → bτ) = 1, and a lower limit on the V LQ3 mass of mV LQ3 > 317 GeV=c2. If theoretical uncertainties on the cross section are applied in the least favorable manner the results are σ < 360fb and mV LQ3 > 294 GeV=c2. The Minimal coupling V LQ3 result is an upper limit on the cross section of σ < 493fb (σ < 610fb) and the lower limit on the mass is mV LQ3 > 251 GeV=c2 (mV LQ3 > 223 GeV=c2) for the nominal (1σ varied) theoretical expectation.

  5. A Note on Magic Squares

    Science.gov (United States)

    Williams, Horace E.

    1974-01-01

    A method for generating 3x3 magic squares is developed. A series of questions relating to these magic squares is posed. An invesitgation using matrix methods is suggested with some questions for consideration. (LS)

  6. Enhancing Pseudo-Telepathy in the Magic Square Game

    Science.gov (United States)

    Pawela, Łukasz; Gawron, Piotr; Puchała, Zbigniew; Sładkowski, Jan

    2013-01-01

    We study the possibility of reversing an action of a quantum channel. Our principal objective is to find a specific channel that reverses as accurately as possible an action of a given quantum channel. To achieve this goal we use semidefinite programming. We show the benefits of our method using the quantum pseudo-telepathy Magic Square game with noise. Our strategy is to move the pseudo-telepathy region to higher noise values. We show that it is possible to reverse the action of a noise channel using semidefinite programming. PMID:23762246

  7. Minimum Mean-Square Error Single-Channel Signal Estimation

    DEFF Research Database (Denmark)

    Beierholm, Thomas

    2008-01-01

    This topic of this thesis is MMSE signal estimation for hearing aids when only one microphone is available. The research is relevant for noise reduction systems in hearing aids. To fully benefit from the amplification provided by a hearing aid, noise reduction functionality is important as hearin...... algorithm. Although performance of the two algorithms is found comparable then the particle filter algorithm is doing a much better job tracking the noise.......-impaired persons in some noisy situations need a higher signal to noise ratio for speech to be intelligible when compared to normal-hearing persons. In this thesis two different methods to approach the MMSE signal estimation problem is examined. The methods differ in the way that models for the signal and noise...... inference is performed by particle filtering. The speech model is a time-varying auto-regressive model reparameterized by formant frequencies and bandwidths. The noise is assumed non-stationary and white. Compared to the case of using the AR coefficients directly then it is found very beneficial to perform...

  8. From Square Dance to Mathematics

    Science.gov (United States)

    Bremer, Zoe

    2010-01-01

    In this article, the author suggests a cross-curricular idea that can link with PE, dance, music and history. Teacher David Schmitz, a maths teacher in Illinois who was also a square dance caller, had developed a maths course that used the standard square dance syllabus to teach mathematical principles. He presents an intensive, two-week course…

  9. Counting Triangles to Sum Squares

    Science.gov (United States)

    DeMaio, Joe

    2012-01-01

    Counting complete subgraphs of three vertices in complete graphs, yields combinatorial arguments for identities for sums of squares of integers, odd integers, even integers and sums of the triangular numbers.

  10. Channel Estimation in DCT-Based OFDM

    Science.gov (United States)

    Wang, Yulin; Zhang, Gengxin; Xie, Zhidong; Hu, Jing

    2014-01-01

    This paper derives the channel estimation of a discrete cosine transform- (DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic. PMID:24757439

  11. A Weighted Least Squares Approach To Robustify Least Squares Estimates.

    Science.gov (United States)

    Lin, Chowhong; Davenport, Ernest C., Jr.

    This study developed a robust linear regression technique based on the idea of weighted least squares. In this technique, a subsample of the full data of interest is drawn, based on a measure of distance, and an initial set of regression coefficients is calculated. The rest of the data points are then taken into the subsample, one after another,…

  12. Sums of squares of integers

    CERN Document Server

    Moreno, Carlos J

    2005-01-01

    Introduction Prerequisites Outline of Chapters 2 - 8 Elementary Methods Introduction Some Lemmas Two Fundamental Identities Euler's Recurrence for Sigma(n)More Identities Sums of Two Squares Sums of Four Squares Still More Identities Sums of Three Squares An Alternate Method Sums of Polygonal Numbers Exercises Bernoulli Numbers Overview Definition of the Bernoulli Numbers The Euler-MacLaurin Sum Formula The Riemann Zeta Function Signs of Bernoulli Numbers Alternate The von Staudt-Clausen Theorem Congruences of Voronoi and Kummer Irregular Primes Fractional Parts of Bernoulli Numbers Exercises Examples of Modular Forms Introduction An Example of Jacobi and Smith An Example of Ramanujan and Mordell An Example of Wilton: t (n) Modulo 23 An Example of Hamburger Exercises Hecke's Theory of Modular FormsIntroduction Modular Group ? and its Subgroup ? 0 (N) Fundamental Domains For ? and ? 0 (N) Integral Modular Forms Modular Forms of Type Mk(? 0(N);chi) and Euler-Poincare series Hecke Operators Dirichlet Series and ...

  13. Graphs whose complement and square are isomorphic

    DEFF Research Database (Denmark)

    Pedersen, Anders Sune

    2014-01-01

    We study square-complementary graphs, that is, graphs whose complement and square are isomorphic. We prove several necessary conditions for a graph to be square-complementary, describe ways of building new square-complementary graphs from existing ones, construct infinite families of square-compl...

  14. Agglomerative clustering of growing squares

    NARCIS (Netherlands)

    Castermans, Thom; Speckmann, Bettina; Staals, Frank; Verbeek, Kevin; Bender, M.A.; Farach-Colton, M.; Mosteiro, M.A.

    2018-01-01

    We study an agglomerative clustering problem motivated by interactive glyphs in geo-visualization. Consider a set of disjoint square glyphs on an interactive map. When the user zooms out, the glyphs grow in size relative to the map, possibly with different speeds. When two glyphs intersect, we wish

  15. On the Sen limit squared

    OpenAIRE

    Fullwood, James; Wang, Dongxu

    2018-01-01

    We introduce a class of F-theory vacua whose smooth elliptic fibers admit a vanishing $j$-invariant, and construct a weak coupling limit associated with such vacua which we view as the `square' of the Sen limit. We find that while Sen's limit is naturally viewed as an orientifold theory, the universal tadpole relation which equates the D3 charge between the associated F-theory compactification and the limit we construct suggests that perhaps the limiting theory is in fact an oriented theory c...

  16. Renaming Zagreb Streets and Squares

    Directory of Open Access Journals (Sweden)

    Jelena Stanić

    2009-06-01

    Full Text Available The paper deals with changes in street names in the city of Zagreb. Taking the Lower Town (Donji grad city area as an example, the first part of the paper analyses diachronic street name changes commencing from the systematic naming of streets in 1878. Analysis of official changes in street names throughout Zagreb’s history resulted in categorisation of five periods of ideologically motivated naming/name-changing: 1. the Croatia modernisation period, when the first official naming was put into effect, with a marked tendency towards politicisation and nationalisation of the urban landscape; 2. the period of the Kingdom of the Serbs, Croatians and Slovenians/Yugoslavia, when symbols of the new monarchy, the idea of the fellowship of the Southern Slavs, Slavenophilism and the pro-Slavic geopolitical orientation were incorporated into the street names, and when the national idea was highly evident and remained so in that process; 3. the period of the NDH, the Independent State of Croatia, with decanonisation of the tokens of the Yugoslavian monarchy and the Southern Slavic orientation, and reference to the Ustashi and the German Nazi and Italian Fascist movement; 4. the period of Socialism, embedding the ideals and heroes of the workers’ movement and the War of National Liberation into the canonical system; and, 5. the period following the democratic changes in 1990, when almost all the signs of Socialism and the Communist/Antifascist struggle were erased, with the prominent presence of a process of installing new references to early national culture and historical tradition. The closing part of the paper deals with public discussions connected with the selection of a location for a square to bear the name of the first president of independent Croatia, Franjo Tuđman. Analysis of these public polemics shows two opposing discourses: the right-wing political option, which supports a central position for the square and considers the chosen area to

  17. Latin squares and their applications

    CERN Document Server

    Keedwell, A Donald

    2015-01-01

    Latin Squares and Their Applications Second edition offers a long-awaited update and reissue of this seminal account of the subject. The revision retains foundational, original material from the frequently-cited 1974 volume but is completely updated throughout. As with the earlier version, the author hopes to take the reader 'from the beginnings of the subject to the frontiers of research'. By omitting a few topics which are no longer of current interest, the book expands upon active and emerging areas. Also, the present state of knowledge regarding the 73 then-unsolved problems given at the

  18. Decreasing vortex flux in channels

    International Nuclear Information System (INIS)

    Migaj, V.K.; Nosova, I.S.

    1979-01-01

    A new method for reducing vortex flow losses in power plant channels is suggested. The method is based on vortex splitting in vortex flow areas with transverse barriers placed on the channel walls. The upper barrier ends are at the level of the upper boundary of the vortex area and don't protrude to the active flow beyond this boundary. The effectiveness of the method suggested is illustrated taking as an example the investigation of square and flat channels with abrupt widening in one plane, diffusers with widening in one plane, or a rectangualr bend. It is shown that splitting the vortex areas with transverse barriers in the channels results in reduction of hydraulic losses by 10-25%. The above method is characteristic of an extreme simplicity, its application doesn't require changes in the channel shape nor installation of any devices in the flow

  19. Squares of Random Linear Codes

    DEFF Research Database (Denmark)

    Cascudo Pueyo, Ignacio; Cramer, Ronald; Mirandola, Diego

    2015-01-01

    a positive answer, for codes of dimension $k$ and length roughly $\\frac{1}{2}k^2$ or smaller. Moreover, the convergence speed is exponential if the difference $k(k+1)/2-n$ is at least linear in $k$. The proof uses random coding and combinatorial arguments, together with algebraic tools involving the precise......Given a linear code $C$, one can define the $d$-th power of $C$ as the span of all componentwise products of $d$ elements of $C$. A power of $C$ may quickly fill the whole space. Our purpose is to answer the following question: does the square of a code ``typically'' fill the whole space? We give...

  20. Ion channeling

    International Nuclear Information System (INIS)

    Erramli, H.; Blondiaux, G.

    1994-01-01

    Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

  1. Square-root measurement for pure states

    International Nuclear Information System (INIS)

    Huang Siendong

    2005-01-01

    Square-root measurement is a very useful suboptimal measurement in many applications. It was shown that the square-root measurement minimizes the squared error for pure states. In this paper, the least squared error problem is reformulated and a new proof is provided. It is found that the least squared error depends only on the average density operator of the input states. The properties of the least squared error are then discussed, and it is shown that if the input pure states are uniformly distributed, the average probability of error has an upper bound depending on the least squared error, the rank of the average density operator, and the number of the input states. The aforementioned properties help explain why the square-root measurement can be effective in decoding processes

  2. 36 CFR 910.67 - Square guidelines.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Square guidelines. 910.67... GUIDELINES AND UNIFORM STANDARDS FOR URBAN PLANNING AND DESIGN OF DEVELOPMENT WITHIN THE PENNSYLVANIA AVENUE DEVELOPMENT AREA Glossary of Terms § 910.67 Square guidelines. Square Guidelines establish the Corporation's...

  3. Channel box

    International Nuclear Information System (INIS)

    Tanabe, Akira.

    1993-01-01

    In a channel box of a BWR type reactor, protruding pads are disposed in axial position on the lateral side of a channel box opposing to a control rod and facing the outer side portion of the control rod in a reactor core loaded state. In the initial loading stage of fuel assemblies, channel fasteners and spacer pads are abutted against each other in the upper portion between the channel boxes sandwiching the control rod therebetween. Further, in the lower portion, a gap as a channel for the movement of the control rod is ensured by the support of fuel support metals. If the channel box is bent toward the control rod along with reactor operation, the pads are abutted against each other to always ensure the gap through which the control rod can move easily. Further, when the pads are brought into contact with each other, the bending deformation of the channel box is corrected by urging to each other. Thus, the control rod can always be moved smoothly to attain reactor safety operation. (N.H.)

  4. Characterization of turbulent coherent structures in square duct flow

    Science.gov (United States)

    Atzori, Marco; Vinuesa, Ricardo; Lozano-Durán, Adrián; Schlatter, Philipp

    2018-04-01

    This work is aimed at a first characterization of coherent structures in turbulent square duct flows. Coherent structures are defined as connected components in the domain identified as places where a quantity of interest (such as Reynolds stress or vorticity) is larger than a prescribed non-uniform threshold. Firstly, we qualitatively discuss how a percolation analysis can be used to assess the effectiveness of the threshold function, and how it can be affected by statistical uncertainty. Secondly, various physical quantities that are expected to play an important role in the dynamics of the secondary flow of Prandtl’s second kind are studied. Furthermore, a characterization of intense Reynolds-stress events in square duct flow, together with a comparison of their shape for analogous events in channel flow at the same Reynolds number, is presented.

  5. Surface channeling

    International Nuclear Information System (INIS)

    Sizmann, R.; Varelas, C.

    1976-01-01

    There is experimental evidence that swift light ions incident at small angles towards single crystalline surfaces can lose an appreciable fraction of their kinetic energy during reflection. It is shown that these projectiles penetrate into the bulk surface region of the crystal. They can travel as channeled particles along long paths through the solid (surface channeling). The angular distribution and the depth history of the re-emerged projectiles are investigated by computer simulations. A considerable fraction of the penetrating projectiles re-emerges from the crystal with constant transverse energy if the angle of incidence is smaller than the critical angle for axial channeling. Analytical formulae are derived based on a diffusion model for surface channeling. A comparison with experimental data exhibits the relevance of the analytical solutions. (Auth.)

  6. Spark Channels

    Energy Technology Data Exchange (ETDEWEB)

    Haydon, S. C. [Department of Physics, University of New England, Armidale, NSW (Australia)

    1968-04-15

    A brief summary is given of the principal methods used for initiating spark channels and the various highly time-resolved techniques developed recently for studies with nanosecond resolution. The importance of the percentage overvoltage in determining the early history and subsequent development of the various phases of the growth of the spark channel is discussed. An account is then given of the recent photographic, oscillographic and spectroscopic investigations of spark channels initiated by co-axial cable discharges of spark gaps at low [{approx} 1%] overvoltages. The phenomena observed in the development of the immediate post-breakdown phase, the diffuse glow structure, the growth of the luminous filament and the final formation of the spark channel in hydrogen are described. A brief account is also given of the salient features emerging from corresponding studies of highly overvolted spark gaps in which the spark channel develops from single avalanche conditions. The essential differences between the two types of channel formation are summarized and possible explanations of the general features are indicated. (author)

  7. Effect of Coriolis and centrifugal forces on flow and heat transfer at high rotation number and high density ratio in non orthogonally internal cooling channel

    Directory of Open Access Journals (Sweden)

    Brahim Berrabah

    2017-02-01

    Full Text Available Numerical predictions of three-dimensional flow and heat transfer are performed for a two-pass square channel with 45° staggered ribs in non-orthogonally mode-rotation using the second moment closure model. At Reynolds number of 25,000, the rotation numbers studied were 0, 0.24, 0.35 and 1.00. The density ratios were 0.13, 0.23 and 0.50. The results show that at high buoyancy parameter and high rotation number with a low density ratio, the flow in the first passage is governed by the secondary flow induced by the rotation whereas the secondary flow induced by the skewed ribs was almost distorted. As a result the heat transfer rate is enhanced on both co-trailing and co-leading sides compared to low and medium rotation number. In contrast, for the second passage, the rotation slightly reduces the heat transfer rate on co-leading side at high rotation number with a low density ratio and degrades it significantly on both co-trailing and co-leading sides at high buoyancy parameter compared to the stationary, low and medium rotation numbers. The numerical results are in fair agreement with available experimental data in the bend region and the second passage, while in the first passage were overestimated at low and medium rotation numbers.

  8. Square pulse linear transformer driver

    Directory of Open Access Journals (Sweden)

    A. A. Kim

    2012-04-01

    Full Text Available The linear transformer driver (LTD technological approach can result in relatively compact devices that can deliver fast, high current, and high-voltage pulses straight out of the LTD cavity without any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The usual LTD architecture [A. A. Kim, M. G. Mazarakis, V. A. Sinebryukhov, B. M. Kovalchuk, V. A. Vizir, S. N Volkov, F. Bayol, A. N. Bastrikov, V. G. Durakov, S. V. Frolov, V. M. Alexeenko, D. H. McDaniel, W. E. Fowler, K. LeCheen, C. Olson, W. A. Stygar, K. W. Struve, J. Porter, and R. M. Gilgenbach, Phys. Rev. ST Accel. Beams 12, 050402 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050402; M. G. Mazarakis, W. E. Fowler, A. A. Kim, V. A. Sinebryukhov, S. T. Rogowski, R. A. Sharpe, D. H. McDaniel, C. L. Olson, J. L. Porter, K. W. Struve, W. A. Stygar, and J. R. Woodworth, Phys. Rev. ST Accel. Beams 12, 050401 (2009PRABFM1098-440210.1103/PhysRevSTAB.12.050401] provides sine shaped output pulses that may not be well suited for some applications like z-pinch drivers, flash radiography, high power microwaves, etc. A more suitable power pulse would have a flat or trapezoidal (rising or falling top. In this paper, we present the design and first test results of an LTD cavity that generates such a type of output pulse by including within its circular array a number of third harmonic bricks in addition to the main bricks. A voltage adder made out of a square pulse cavity linear array will produce the same shape output pulses provided that the timing of each cavity is synchronized with the propagation of the electromagnetic pulse.

  9. Weighted conditional least-squares estimation

    International Nuclear Information System (INIS)

    Booth, J.G.

    1987-01-01

    A two-stage estimation procedure is proposed that generalizes the concept of conditional least squares. The method is instead based upon the minimization of a weighted sum of squares, where the weights are inverses of estimated conditional variance terms. Some general conditions are given under which the estimators are consistent and jointly asymptotically normal. More specific details are given for ergodic Markov processes with stationary transition probabilities. A comparison is made with the ordinary conditional least-squares estimators for two simple branching processes with immigration. The relationship between weighted conditional least squares and other, more well-known, estimators is also investigated. In particular, it is shown that in many cases estimated generalized least-squares estimators can be obtained using the weighted conditional least-squares approach. Applications to stochastic compartmental models, and linear models with nested error structures are considered

  10. Downlink Channel Estimation in Cellular Systems with Antenna Arrays at Base Stations Using Channel Probing with Feedback

    Directory of Open Access Journals (Sweden)

    Biguesh Mehrzad

    2004-01-01

    Full Text Available In mobile communication systems with multisensor antennas at base stations, downlink channel estimation plays a key role because accurate channel estimates are needed for transmit beamforming. One efficient approach to this problem is channel probing with feedback. In this method, the base station array transmits probing (training signals. The channel is then estimated from feedback reports provided by the users. This paper studies the performance of the channel probing method with feedback using a multisensor base station antenna array and single-sensor users. The least squares (LS, linear minimum mean square error (LMMSE, and a new scaled LS (SLS approaches to the channel estimation are studied. Optimal choice of probing signals is investigated for each of these techniques and their channel estimation performances are analyzed. In the case of multiple LS channel estimates, the best linear unbiased estimation (BLUE scheme for their linear combining is developed and studied.

  11. Sets of Mutually Orthogonal Sudoku Latin Squares

    Science.gov (United States)

    Vis, Timothy; Petersen, Ryan M.

    2009-01-01

    A Latin square of order "n" is an "n" x "n" array using n symbols, such that each symbol appears exactly once in each row and column. A set of Latin squares is c ordered pairs of symbols appearing in the cells of the array are distinct. The popular puzzle Sudoku involves Latin squares with n = 9, along with the added condition that each of the 9…

  12. The Square Light Clock and Special Relativity

    Science.gov (United States)

    Galli, J. Ronald; Amiri, Farhang

    2012-01-01

    A thought experiment that includes a square light clock is similar to the traditional vertical light beam and mirror clock, except it is made up of four mirrors placed at a 45[degree] angle at each corner of a square of length L[subscript 0], shown in Fig. 1. Here we have shown the events as measured in the rest frame of the square light clock. By…

  13. Comparison of Pilot Symbol Embedded Channel Estimation Algorithms

    Directory of Open Access Journals (Sweden)

    P. Kadlec

    2009-12-01

    Full Text Available In the paper, algorithms of the pilot symbol embedded channel estimation are compared. Attention is turned to the Least Square (LS channel estimation and the Sliding Correlator (SC algorithm. Both algorithms are implemented in Matlab to estimate the Channel Impulse Response (CIR of a channel exhibiting multi-path propagation. Algorithms are compared from the viewpoint of computational demands, influence of the Additive White Gaussian Noise (AWGN, an embedded pilot symbol and a computed CIR over the estimation error.

  14. MARKETING CHANNELS

    Directory of Open Access Journals (Sweden)

    Ljiljana Stošić Mihajlović

    2014-07-01

    Full Text Available Marketing channel is a set of entities and institutions, completion of distribution and marketing activities, attend the efficient and effective networking of producers and consumers. Marketing channels include the total flows of goods, money and information taking place between the institutions in the system of marketing, establishing a connection between them. The functions of the exchange, the physical supply and service activities, inherent in the system of marketing and trade. They represent paths which products and services are moving after the production, which will ultimately end up buying and eating by the user.

  15. Wave-equation Q tomography and least-squares migration

    KAUST Repository

    Dutta, Gaurav

    2016-03-01

    This thesis designs new methods for Q tomography and Q-compensated prestack depth migration when the recorded seismic data suffer from strong attenuation. A motivation of this work is that the presence of gas clouds or mud channels in overburden structures leads to the distortion of amplitudes and phases in seismic waves propagating inside the earth. If the attenuation parameter Q is very strong, i.e., Q<30, ignoring the anelastic effects in imaging can lead to dimming of migration amplitudes and loss of resolution. This, in turn, adversely affects the ability to accurately predict reservoir properties below such layers. To mitigate this problem, I first develop an anelastic least-squares reverse time migration (Q-LSRTM) technique. I reformulate the conventional acoustic least-squares migration problem as a viscoacoustic linearized inversion problem. Using linearized viscoacoustic modeling and adjoint operators during the least-squares iterations, I show with numerical tests that Q-LSRTM can compensate for the amplitude loss and produce images with better balanced amplitudes than conventional migration. To estimate the background Q model that can be used for any Q-compensating migration algorithm, I then develop a wave-equation based optimization method that inverts for the subsurface Q distribution by minimizing a skeletonized misfit function ε. Here, ε is the sum of the squared differences between the observed and the predicted peak/centroid-frequency shifts of the early-arrivals. Through numerical tests on synthetic and field data, I show that noticeable improvements in the migration image quality can be obtained from Q models inverted using wave-equation Q tomography. A key feature of skeletonized inversion is that it is much less likely to get stuck in a local minimum than a standard waveform inversion method. Finally, I develop a preconditioning technique for least-squares migration using a directional Gabor-based preconditioning approach for isotropic

  16. DFT-based channel estimation and noise variance estimation techniques for single-carrier FDMA

    OpenAIRE

    Huang, G; Nix, AR; Armour, SMD

    2010-01-01

    Practical frequency domain equalization (FDE) systems generally require knowledge of the channel and the noise variance to equalize the received signal in a frequency-selective fading channel. Accurate channel estimate and noise variance estimate are thus desirable to improve receiver performance. In this paper we investigate the performance of the denoise channel estimator and the approximate linear minimum mean square error (A-LMMSE) channel estimator with channel power delay profile (PDP) ...

  17. Distribution of squares modulo a composite number

    OpenAIRE

    Aryan, Farzad

    2015-01-01

    In this paper we study the distribution of squares modulo a square-free number $q$. We also look at inverse questions for the large sieve in the distribution aspect and we make improvements on existing results on the distribution of $s$-tuples of reduced residues.

  18. Some Theoretical Essences of Lithuania Squares Formation

    Directory of Open Access Journals (Sweden)

    Gintautas Tiškus

    2016-04-01

    Full Text Available In the Lithuanian acts of law and in the scientific literature there are no clear criteria and notions to define a square. The unbuilt city space places or the gaps between buildings are often defined as the squares, which do not have clear limits or destination. The mandatory attributes of the place which is called the square are indicated in the article, the notion of square is defined. The article deals with Lithuanian squares theme, analyses the differences between representation and representativeness. The article aims to indicate an influence of city environmental context and monument in the square on its function. The square is an independent element of city plan structure, but it is not an independent element of city spatial structure. The space and environment of the square are related to each other not only by physical, aesthetical relations, but as well as by causalities, which may be named as the essences of squares’ formation. The interdisciplinary discourse analysis method is applied in the article.

  19. Entrywise Squared Transforms for GAMP Supplementary Material

    DEFF Research Database (Denmark)

    2016-01-01

    Supplementary material for a study on Entrywise Squared Transforms for Generalized Approximate Message Passing (GAMP). See the README file for the details.......Supplementary material for a study on Entrywise Squared Transforms for Generalized Approximate Message Passing (GAMP). See the README file for the details....

  20. Lagrange’s Four-Square Theorem

    Directory of Open Access Journals (Sweden)

    Watase Yasushige

    2015-02-01

    Full Text Available This article provides a formalized proof of the so-called “the four-square theorem”, namely any natural number can be expressed by a sum of four squares, which was proved by Lagrange in 1770. An informal proof of the theorem can be found in the number theory literature, e.g. in [14], [1] or [23].

  1. Improved Sparse Channel Estimation for Cooperative Communication Systems

    Directory of Open Access Journals (Sweden)

    Guan Gui

    2012-01-01

    Full Text Available Accurate channel state information (CSI is necessary at receiver for coherent detection in amplify-and-forward (AF cooperative communication systems. To estimate the channel, traditional methods, that is, least squares (LS and least absolute shrinkage and selection operator (LASSO, are based on assumptions of either dense channel or global sparse channel. However, LS-based linear method neglects the inherent sparse structure information while LASSO-based sparse channel method cannot take full advantage of the prior information. Based on the partial sparse assumption of the cooperative channel model, we propose an improved channel estimation method with partial sparse constraint. At first, by using sparse decomposition theory, channel estimation is formulated as a compressive sensing problem. Secondly, the cooperative channel is reconstructed by LASSO with partial sparse constraint. Finally, numerical simulations are carried out to confirm the superiority of proposed methods over global sparse channel estimation methods.

  2. BIOMECHANICS. Why the seahorse tail is square.

    Science.gov (United States)

    Porter, Michael M; Adriaens, Dominique; Hatton, Ross L; Meyers, Marc A; McKittrick, Joanna

    2015-07-03

    Whereas the predominant shapes of most animal tails are cylindrical, seahorse tails are square prisms. Seahorses use their tails as flexible grasping appendages, in spite of a rigid bony armor that fully encases their bodies. We explore the mechanics of two three-dimensional-printed models that mimic either the natural (square prism) or hypothetical (cylindrical) architecture of a seahorse tail to uncover whether or not the square geometry provides any functional advantages. Our results show that the square prism is more resilient when crushed and provides a mechanism for preserving articulatory organization upon extensive bending and twisting, as compared with its cylindrical counterpart. Thus, the square architecture is better than the circular one in the context of two integrated functions: grasping ability and crushing resistance. Copyright © 2015, American Association for the Advancement of Science.

  3. Degenerated-Inverse-Matrix-Based Channel Estimation for OFDM Systems

    Directory of Open Access Journals (Sweden)

    Makoto Yoshida

    2009-01-01

    Full Text Available This paper addresses time-domain channel estimation for pilot-symbol-aided orthogonal frequency division multiplexing (OFDM systems. By using a cyclic sinc-function matrix uniquely determined by Nc transmitted subcarriers, the performance of our proposed scheme approaches perfect channel state information (CSI, within a maximum of 0.4 dB degradation, regardless of the delay spread of the channel, Doppler frequency, and subcarrier modulation. Furthermore, reducing the matrix size by splitting the dispersive channel impulse response into clusters means that the degenerated inverse matrix estimator (DIME is feasible for broadband, high-quality OFDM transmission systems. In addition to theoretical analysis on normalized mean squared error (NMSE performance of DIME, computer simulations over realistic nonsample spaced channels also showed that the DIME is robust for intersymbol interference (ISI channels and fast time-invariant channels where a minimum mean squared error (MMSE estimator does not work well.

  4. Channel Power in Multi-Channel Environments

    NARCIS (Netherlands)

    M.G. Dekimpe (Marnik); B. Skiera (Bernd)

    2004-01-01

    textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

  5. Around and Beyond the Square of Opposition

    CERN Document Server

    Béziau, Jean-Yves

    2012-01-01

    aiThe theory of oppositions based on Aristotelian foundations of logic has been pictured in a striking square diagram which can be understood and applied in many different ways having repercussions in various fields: epistemology, linguistics, mathematics, psychology. The square can also be generalized in other two-dimensional or multi-dimensional objects extending in breadth and depth the original theory of oppositions of Aristotle. The square of opposition is a very attractive theme which has been going through centuries without evaporating. Since 10 years there is a new growing interest for

  6. Elmo bumpy square plasma confinement device

    Science.gov (United States)

    Owen, L.W.

    1985-01-01

    The invention is an Elmo bumpy type plasma confinement device having a polygonal configuration of closed magnet field lines for improved plasma confinement. In the preferred embodiment, the device is of a square configuration which is referred to as an Elmo bumpy square (EBS). The EBS is formed by four linear magnetic mirror sections each comprising a plurality of axisymmetric assemblies connected in series and linked by 90/sup 0/ sections of a high magnetic field toroidal solenoid type field generating coils. These coils provide corner confinement with a minimum of radial dispersion of the confined plasma to minimize the detrimental effects of the toroidal curvature of the magnetic field. Each corner is formed by a plurality of circular or elliptical coils aligned about the corner radius to provide maximum continuity in the closing of the magnetic field lines about the square configuration confining the plasma within a vacuum vessel located within the various coils forming the square configuration confinement geometry.

  7. Quantized kernel least mean square algorithm.

    Science.gov (United States)

    Chen, Badong; Zhao, Songlin; Zhu, Pingping; Príncipe, José C

    2012-01-01

    In this paper, we propose a quantization approach, as an alternative of sparsification, to curb the growth of the radial basis function structure in kernel adaptive filtering. The basic idea behind this method is to quantize and hence compress the input (or feature) space. Different from sparsification, the new approach uses the "redundant" data to update the coefficient of the closest center. In particular, a quantized kernel least mean square (QKLMS) algorithm is developed, which is based on a simple online vector quantization method. The analytical study of the mean square convergence has been carried out. The energy conservation relation for QKLMS is established, and on this basis we arrive at a sufficient condition for mean square convergence, and a lower and upper bound on the theoretical value of the steady-state excess mean square error. Static function estimation and short-term chaotic time-series prediction examples are presented to demonstrate the excellent performance.

  8. Anomalous structural transition of confined hard squares.

    Science.gov (United States)

    Gurin, Péter; Varga, Szabolcs; Odriozola, Gerardo

    2016-11-01

    Structural transitions are examined in quasi-one-dimensional systems of freely rotating hard squares, which are confined between two parallel walls. We find two competing phases: one is a fluid where the squares have two sides parallel to the walls, while the second one is a solidlike structure with a zigzag arrangement of the squares. Using transfer matrix method we show that the configuration space consists of subspaces of fluidlike and solidlike phases, which are connected with low probability microstates of mixed structures. The existence of these connecting states makes the thermodynamic quantities continuous and precludes the possibility of a true phase transition. However, thermodynamic functions indicate strong tendency for the phase transition and our replica exchange Monte Carlo simulation study detects several important markers of the first order phase transition. The distinction of a phase transition from a structural change is practically impossible with simulations and experiments in such systems like the confined hard squares.

  9. The inverse square law of gravitation

    International Nuclear Information System (INIS)

    Cook, A.H.

    1987-01-01

    The inverse square law of gravitation is very well established over the distances of celestial mechanics, while in electrostatics the law has been shown to be followed to very high precision. However, it is only within the last century that any laboratory experiments have been made to test the inverse square law for gravitation, and all but one has been carried out in the last ten years. At the same time, there has been considerable interest in the possibility of deviations from the inverse square law, either because of a possible bearing on unified theories of forces, including gravitation or, most recently, because of a possible additional fifth force of nature. In this article the various lines of evidence for the inverse square law are summarized, with emphasis upon the recent laboratory experiments. (author)

  10. Applications of square-related theorems

    Science.gov (United States)

    Srinivasan, V. K.

    2014-04-01

    The square centre of a given square is the point of intersection of its two diagonals. When two squares of different side lengths share the same square centre, there are in general four diagonals that go through the same square centre. The Two Squares Theorem developed in this paper summarizes some nice theoretical conclusions that can be obtained when two squares of different side lengths share the same square centre. These results provide the theoretical basis for two of the constructions given in the book of H.S. Hall and F.H. Stevens , 'A Shorter School Geometry, Part 1, Metric Edition'. In page 134 of this book, the authors present, in exercise 4, a practical construction which leads to a verification of the Pythagorean theorem. Subsequently in Theorems 29 and 30, the authors present the standard proofs of the Pythagorean theorem and its converse. In page 140, the authors present, in exercise 15, what amounts to a geometric construction, whose verification involves a simple algebraic identity. Both the constructions are of great importance and can be replicated by using the standard equipment provided in a 'geometry toolbox' carried by students in high schools. The author hopes that the results proved in this paper, in conjunction with the two constructions from the above-mentioned book, would provide high school students an appreciation of the celebrated theorem of Pythagoras. The diagrams that accompany this document are based on the free software GeoGebra. The author formally acknowledges his indebtedness to the creators of this free software at the end of this document.

  11. Power Efficient Division and Square Root Unit

    DEFF Research Database (Denmark)

    Liu, Wei; Nannarelli, Alberto

    2012-01-01

    Although division and square root are not frequent operations, most processors implement them in hardware to not compromise the overall performance. Two classes of algorithms implement division or square root: digit-recurrence and multiplicative (e.g., Newton-Raphson) algorithms. Previous work....... The proposed unit is compared to similar solutions based on the digit-recurrence algorithm and it is compared to a unit based on the multiplicative Newton-Raphson algorithm....

  12. Channelling and electromagnetic radiation of channelling particles

    International Nuclear Information System (INIS)

    Kalashnikov, N.

    1983-01-01

    A brief description is presented of the channelling of charged particles between atoms in the crystal lattice. The specificities are discussed of the transverse motion of channelling particles as are the origin and properties of quasi-characteristic radiation of channelling particles which accompany transfers from one band of permissible energies of the transverse motion of channelling particles to the other. (B.S.)

  13. Channel Modeling

    Science.gov (United States)

    Schmitz, Arne; Schinnenburg, Marc; Gross, James; Aguiar, Ana

    For any communication system the Signal-to-Interference-plus-Noise-Ratio of the link is a fundamental metric. Recall (cf. Chapter 9) that the SINR is defined as the ratio between the received power of the signal of interest and the sum of all "disturbing" power sources (i.e. interference and noise). From information theory it is known that a higher SINR increases the maximum possible error-free transmission rate (referred to as Shannon capacity [417] of any communication system and vice versa). Conversely, the higher the SINR, the lower will be the bit error rate in practical systems. While one aspect of the SINR is the sum of all distracting power sources, another issue is the received power. This depends on the transmitted power, the used antennas, possibly on signal processing techniques and ultimately on the channel gain between transmitter and receiver.

  14. Channeling experiment

    International Nuclear Information System (INIS)

    Abelin, H.; Birgersson, L.; Widen, H.; Aagren, T.; Moreno, L.; Neretnieks, I.

    1990-07-01

    Channeling of water flow and tracer transport in real fractures in a granite body at Stripa have been investigated experimentally. The experimental site was located 360 m below the ground level. Two kinds of experiments were performed. In the single hole experiments, 20 cm diameter holes were drilled about 2.5 m into the rock in the plane of the fracture. Specially designed packers were used to inject water into the fracture in 5 cm intervals all along the fracture trace in the hole. The variation of the injection flowrates along the fracture were used to determine the transmissivity variations in the fracture plane. Detailed photographs were taken from inside the hole and the visual fracture aperture was compared with the injection flowrates in the same locations. Geostatistical methods were used to evaluate the results. Five holes were measured in great detail. In addition 7 holes were drilled and scanned by simpler packer systems. A double hole experiment was performed where two parallel holes were drilled in the same fracture plane at nearly 2 m distance. Pressure pulse tests were made between the holes in both directions. Tracers were injected in 5 locations in one hole and monitored for in many locations in the other hole. The single hole experiment and the double hole experiment show that most of the fracture planes are tight but that there are open sections which form connected channels over distances of at least 2 meters. It was also found in the double hole experiment that the investigated fracture was intersected by at least one fracture between the two holes which diverted a large amount of the injected tracers to several distant locations at the tunnel wall. (authours)

  15. On the domestic fuel channel for BWR

    International Nuclear Information System (INIS)

    Fukada, Hiroshi

    1979-01-01

    Kobe Steel Ltd. started the domestic manufacture of fuel channel boxes for BWRs in 1967, and entered the actual production stage four years after that. Since 1976, the mass production system was adopted with the increase of the demand. The requirements about the surface contamination and the dimensional accuracy over whole length are very strict in the fuel channel boxes, moreover, special consideration must be given so as to prevent the deformation in use. The unique working methods such as electron beam welding, high temperature press forming and so on are employed in Kobe Steel Ltd. to satisfy such strict requirements, therefore the quality of the produced fuel channel boxes is superior to imported ones. At present, the fuel channel boxes domestically made by Kobe Steel Ltd. are used for almost all BWRs in Japan. The functions of fuel channel boxes are to flow boiling coolant uniformly upward, to guide control rods, and to increase the rigidity of fuel assembly. The fuel channel boxes are the square tubes of zircaloy 4 of 134.06 mm inside width, 2.03 mm thickness, and 4118 or 4239 mm length. The progress of the development and the features of the fuel channel boxes and the manufacturing processes are described. Zircaloy plates are formed into channels, and two channels are electron beam-welded after the edge preparation, to make a box. Ultrasonic examination and stress relief treatment are applied, and clips and spacers are welded. (Kako, I.)

  16. Condensation in a Square Minichannel: Application of the VOF Method

    CERN Document Server

    Bortolin, V; Del Col, Davide

    2014-01-01

    A number of steady-state numerical simulations of condensation of R134a at mass fluxes of 400 kg m−2 s−1 and 800 kg m−2 s−1 inside a 1-mm square cross section minichannel are proposed here and compared against simulations in a circular cross section channel with the same hydraulic diameter. The volume of fluid (VOF) method is used to track the vapor–liquid interface, and the effects of interfacial shear stress, surface tension, and gravity are taken into account. A uniform wall temperature is fixed as a boundary condition. At both mass velocities the liquid film and the vapor core are treated as turbulent; a low-Re form of the SST k-ω model has been used for the modeling of turbulence through both the liquid and vapor phases. Numerical simulations are validated against experimental data. The influence of the surface tension on the shape of the vapor–liquid interface may provide some heat transfer enhancement in a square cross section minichannel, but this depends on the mass flux and it may be no...

  17. Non-spill control squared cascade

    International Nuclear Information System (INIS)

    Kai, Tsunetoshi; Inoue, Yoshiya; Oya, Akio; Suemori, Nobuo.

    1974-01-01

    Object: To reduce a mixed loss thus enhancing separating efficiency by the provision of a simple arrangement wherein a reflux portion in a conventional spill control squared cascade is replaced by a special stage including centrifugal separators. Structure: Steps in the form of a square cascade, in which a plurality of centrifugal separators are connected by pipe lines, are accumulated in multistage fashion to form a squared cascade. Between the adjoining steps is disposed a special stage including a centrifugal separator which receives both lean flow from the upper step and rich flow from the lower step. The centrifugal separator in the special stage has its rich side connected to the upper step and its lean side connected to the lower step. Special stages are each disposed at the upper side of the uppermost step and at the lower side of the lowermost step. (Kamimura, M.)

  18. Least Squares Data Fitting with Applications

    DEFF Research Database (Denmark)

    Hansen, Per Christian; Pereyra, Víctor; Scherer, Godela

    As one of the classical statistical regression techniques, and often the first to be taught to new students, least squares fitting can be a very effective tool in data analysis. Given measured data, we establish a relationship between independent and dependent variables so that we can use the data....... In a number of applications, the accuracy and efficiency of the least squares fit is central, and Per Christian Hansen, Víctor Pereyra, and Godela Scherer survey modern computational methods and illustrate them in fields ranging from engineering and environmental sciences to geophysics. Anyone working...... with problems of linear and nonlinear least squares fitting will find this book invaluable as a hands-on guide, with accessible text and carefully explained problems. Included are • an overview of computational methods together with their properties and advantages • topics from statistical regression analysis...

  19. Good Filtrations and the Steinberg Square

    DEFF Research Database (Denmark)

    Kildetoft, Tobias

    that tensoring the Steinberg module with a simple module of restricted highest weight gives a module with a good filtration. This result was first proved by Andersen when the characteristic is large enough. In this dissertation, generalizations of those results, which are joint work with Daniel Nakano......, the socle completely determines how a Steinberg square decomposes. The dissertation also investigates the socle of the Steinberg square for a finite group of Lie type, again providing formulas which describe how to find the multiplicity of a simple module in the socle, given information about...

  20. Self-diffusion of particles interacting through a square-well or square-shoulder potential

    NARCIS (Netherlands)

    Wilbertz, H.; Michels, J.; Beijeren, H. van; Leegwater, J.A.

    1988-01-01

    The diffusion coefficient and velocity autocorrelation function for a fluid of particles interacting through a square-well or square-shoulder potential are calculated from a kinetic theory similar to the Davis-Rice-Sengers theory and the results are compared to those of computer simulations. At low

  1. Multiples least-squares reverse time migration

    KAUST Repository

    Zhang, Dongliang; Zhan, Ge; Dai, Wei; Schuster, Gerard T.

    2013-01-01

    To enhance the image quality, we propose multiples least-squares reverse time migration (MLSRTM) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. Since each recorded trace is treated

  2. Least-squares variance component estimation

    NARCIS (Netherlands)

    Teunissen, P.J.G.; Amiri-Simkooei, A.R.

    2007-01-01

    Least-squares variance component estimation (LS-VCE) is a simple, flexible and attractive method for the estimation of unknown variance and covariance components. LS-VCE is simple because it is based on the well-known principle of LS; it is flexible because it works with a user-defined weight

  3. Latin square three dimensional gage master

    Science.gov (United States)

    Jones, Lynn L.

    1982-01-01

    A gage master for coordinate measuring machines has an nxn array of objects distributed in the Z coordinate utilizing the concept of a Latin square experimental design. Using analysis of variance techniques, the invention may be used to identify sources of error in machine geometry and quantify machine accuracy.

  4. Time Scale in Least Square Method

    Directory of Open Access Journals (Sweden)

    Özgür Yeniay

    2014-01-01

    Full Text Available Study of dynamic equations in time scale is a new area in mathematics. Time scale tries to build a bridge between real numbers and integers. Two derivatives in time scale have been introduced and called as delta and nabla derivative. Delta derivative concept is defined as forward direction, and nabla derivative concept is defined as backward direction. Within the scope of this study, we consider the method of obtaining parameters of regression equation of integer values through time scale. Therefore, we implemented least squares method according to derivative definition of time scale and obtained coefficients related to the model. Here, there exist two coefficients originating from forward and backward jump operators relevant to the same model, which are different from each other. Occurrence of such a situation is equal to total number of values of vertical deviation between regression equations and observation values of forward and backward jump operators divided by two. We also estimated coefficients for the model using ordinary least squares method. As a result, we made an introduction to least squares method on time scale. We think that time scale theory would be a new vision in least square especially when assumptions of linear regression are violated.

  5. Group-wise partial least square regression

    NARCIS (Netherlands)

    Camacho, José; Saccenti, Edoardo

    2018-01-01

    This paper introduces the group-wise partial least squares (GPLS) regression. GPLS is a new sparse PLS technique where the sparsity structure is defined in terms of groups of correlated variables, similarly to what is done in the related group-wise principal component analysis. These groups are

  6. Clar sextets in square graphene antidot lattices

    DEFF Research Database (Denmark)

    Petersen, Rene; Pedersen, Thomas Garm; Jauho, Antti-Pekka

    2011-01-01

    A periodic array of holes transforms graphene from a semimetal into a semiconductor with a band gap tuneable by varying the parameters of the lattice. In earlier work only hexagonal lattices have been treated. Using atomistic models we here investigate the size of the band gap of a square lattice...

  7. Deformation analysis with Total Least Squares

    Directory of Open Access Journals (Sweden)

    M. Acar

    2006-01-01

    Full Text Available Deformation analysis is one of the main research fields in geodesy. Deformation analysis process comprises measurement and analysis phases. Measurements can be collected using several techniques. The output of the evaluation of the measurements is mainly point positions. In the deformation analysis phase, the coordinate changes in the point positions are investigated. Several models or approaches can be employed for the analysis. One approach is based on a Helmert or similarity coordinate transformation where the displacements and the respective covariance matrix are transformed into a unique datum. Traditionally a Least Squares (LS technique is used for the transformation procedure. Another approach that could be introduced as an alternative methodology is the Total Least Squares (TLS that is considerably a new approach in geodetic applications. In this study, in order to determine point displacements, 3-D coordinate transformations based on the Helmert transformation model were carried out individually by the Least Squares (LS and the Total Least Squares (TLS, respectively. The data used in this study was collected by GPS technique in a landslide area located nearby Istanbul. The results obtained from these two approaches have been compared.

  8. Optimistic semi-supervised least squares classification

    DEFF Research Database (Denmark)

    Krijthe, Jesse H.; Loog, Marco

    2017-01-01

    The goal of semi-supervised learning is to improve supervised classifiers by using additional unlabeled training examples. In this work we study a simple self-learning approach to semi-supervised learning applied to the least squares classifier. We show that a soft-label and a hard-label variant ...

  9. Iterative methods for weighted least-squares

    Energy Technology Data Exchange (ETDEWEB)

    Bobrovnikova, E.Y.; Vavasis, S.A. [Cornell Univ., Ithaca, NY (United States)

    1996-12-31

    A weighted least-squares problem with a very ill-conditioned weight matrix arises in many applications. Because of round-off errors, the standard conjugate gradient method for solving this system does not give the correct answer even after n iterations. In this paper we propose an iterative algorithm based on a new type of reorthogonalization that converges to the solution.

  10. Least-squares model-based halftoning

    Science.gov (United States)

    Pappas, Thrasyvoulos N.; Neuhoff, David L.

    1992-08-01

    A least-squares model-based approach to digital halftoning is proposed. It exploits both a printer model and a model for visual perception. It attempts to produce an 'optimal' halftoned reproduction, by minimizing the squared error between the response of the cascade of the printer and visual models to the binary image and the response of the visual model to the original gray-scale image. Conventional methods, such as clustered ordered dither, use the properties of the eye only implicitly, and resist printer distortions at the expense of spatial and gray-scale resolution. In previous work we showed that our printer model can be used to modify error diffusion to account for printer distortions. The modified error diffusion algorithm has better spatial and gray-scale resolution than conventional techniques, but produces some well known artifacts and asymmetries because it does not make use of an explicit eye model. Least-squares model-based halftoning uses explicit eye models and relies on printer models that predict distortions and exploit them to increase, rather than decrease, both spatial and gray-scale resolution. We have shown that the one-dimensional least-squares problem, in which each row or column of the image is halftoned independently, can be implemented with the Viterbi's algorithm. Unfortunately, no closed form solution can be found in two dimensions. The two-dimensional least squares solution is obtained by iterative techniques. Experiments show that least-squares model-based halftoning produces more gray levels and better spatial resolution than conventional techniques. We also show that the least- squares approach eliminates the problems associated with error diffusion. Model-based halftoning can be especially useful in transmission of high quality documents using high fidelity gray-scale image encoders. As we have shown, in such cases halftoning can be performed at the receiver, just before printing. Apart from coding efficiency, this approach

  11. RLS Channel Estimation with Adaptive Forgetting Factor for DS-CDMA Frequency-Domain Equalization

    Science.gov (United States)

    Kojima, Yohei; Tomeba, Hiromichi; Takeda, Kazuaki; Adachi, Fumiyuki

    Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can increase the downlink bit error rate (BER) performance of DS-CDMA beyond that possible with conventional rake combining in a frequency-selective fading channel. FDE requires accurate channel estimation. Recently, we proposed a pilot-assisted channel estimation (CE) based on the MMSE criterion. Using MMSE-CE, the channel estimation accuracy is almost insensitive to the pilot chip sequence, and a good BER performance is achieved. In this paper, we propose a channel estimation scheme using one-tap recursive least square (RLS) algorithm, where the forgetting factor is adapted to the changing channel condition by the least mean square (LMS)algorithm, for DS-CDMA with FDE. We evaluate the BER performance using RLS-CE with adaptive forgetting factor in a frequency-selective fast Rayleigh fading channel by computer simulation.

  12. Optimization of Training Signal Transmission for Estimating MIMO Channel under Antenna Mutual Coupling Conditions

    Directory of Open Access Journals (Sweden)

    Xia Liu

    2010-01-01

    Full Text Available This paper reports investigations on the effect of antenna mutual coupling on performance of training-based Multiple-Input Multiple-Output (MIMO channel estimation. The influence of mutual coupling is assessed for two training-based channel estimation methods, Scaled Least Square (SLS and Minimum Mean Square Error (MMSE. It is shown that the accuracy of MIMO channel estimation is governed by the sum of eigenvalues of channel correlation matrix which in turn is influenced by the mutual coupling in transmitting and receiving array antennas. A water-filling-based procedure is proposed to optimize the training signal transmission to minimize the MIMO channel estimation errors.

  13. Mathematical Construction of Magic Squares Utilizing Base-N Arithmetic

    Science.gov (United States)

    O'Brien, Thomas D.

    2006-01-01

    Magic squares have been of interest as a source of recreation for over 4,500 years. A magic square consists of a square array of n[squared] positive and distinct integers arranged so that the sum of any column, row, or main diagonal is the same. In particular, an array of consecutive integers from 1 to n[squared] forming an nxn magic square is…

  14. Relative ordering of square-norm distance correlations in open quantum systems

    International Nuclear Information System (INIS)

    Wu Tao; Song Xue-Ke; Ye Liu

    2014-01-01

    We investigate the square-norm distance correlation dynamics of the Bell-diagonal states under different local decoherence channels, including phase flip, bit flip, and bit-phase flip channels by employing the geometric discord (GD) and its modified geometric discord (MGD), as the measures of the square-norm distance correlations. Moreover, an explicit comparison between them is made in detail. The results show that there is no distinct dominant relative ordering between them. Furthermore, we obtain that the GD just gradually deceases to zero, while MGD initially has a large freezing interval, and then suddenly changes in evolution. The longer the freezing interval, the less the MGD is. Interestingly, it is shown that the dynamic behaviors of the two geometric discords under the three noisy environments for the Werner-type initial states are the same. (general)

  15. Square root metric in the analysis of the measurements of high energy physics instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Petrillo, L; Severi, M [Istituto Nazionale di Fisica Nucleare, Rome (Italy); Rome Univ. (Italy). Ist. di Fisica)

    1982-09-15

    A vast category of detectors are characterized by a charge output with a distribution which has a variance proportional to the mean value. In all these cases a square root scale achieved in the hardware seems more suitable from the point of view of the resolution of the measurements, of the number of ADC channels needed, and of a preliminary analysis in the stage of tuning and checking of the detector.

  16. Regularization by truncated total least squares

    DEFF Research Database (Denmark)

    Hansen, Per Christian; Fierro, R.D; Golub, G.H

    1997-01-01

    The total least squares (TLS) method is a successful method for noise reduction in linear least squares problems in a number of applications. The TLS method is suited to problems in which both the coefficient matrix and the right-hand side are not precisely known. This paper focuses on the use...... schemes for relativistic hydrodynamical equations. Such an approximate Riemann solver is presented in this paper which treats all waves emanating from an initial discontinuity as themselves discontinuous. Therefore, jump conditions for shocks are approximately used for rarefaction waves. The solver...... is easy to implement in a Godunov scheme and converges rapidly for relativistic hydrodynamics. The fast convergence of the solver indicates the potential of a higher performance of a Godunov scheme in which the solver is used....

  17. Total least squares for anomalous change detection

    Science.gov (United States)

    Theiler, James; Matsekh, Anna M.

    2010-04-01

    A family of subtraction-based anomalous change detection algorithms is derived from a total least squares (TLSQ) framework. This provides an alternative to the well-known chronochrome algorithm, which is derived from ordinary least squares. In both cases, the most anomalous changes are identified with the pixels that exhibit the largest residuals with respect to the regression of the two images against each other. The family of TLSQbased anomalous change detectors is shown to be equivalent to the subspace RX formulation for straight anomaly detection, but applied to the stacked space. However, this family is not invariant to linear coordinate transforms. On the other hand, whitened TLSQ is coordinate invariant, and special cases of it are equivalent to canonical correlation analysis and optimized covariance equalization. What whitened TLSQ offers is a generalization of these algorithms with the potential for better performance.

  18. Constrained least squares regularization in PET

    International Nuclear Information System (INIS)

    Choudhury, K.R.; O'Sullivan, F.O.

    1996-01-01

    Standard reconstruction methods used in tomography produce images with undesirable negative artifacts in background and in areas of high local contrast. While sophisticated statistical reconstruction methods can be devised to correct for these artifacts, their computational implementation is excessive for routine operational use. This work describes a technique for rapid computation of approximate constrained least squares regularization estimates. The unique feature of the approach is that it involves no iterative projection or backprojection steps. This contrasts with the familiar computationally intensive algorithms based on algebraic reconstruction (ART) or expectation-maximization (EM) methods. Experimentation with the new approach for deconvolution and mixture analysis shows that the root mean square error quality of estimators based on the proposed algorithm matches and usually dominates that of more elaborate maximum likelihood, at a fraction of the computational effort

  19. Classical square-plus-triangle well fluid

    International Nuclear Information System (INIS)

    Boghdadi, M.

    1984-01-01

    A simplified model for the intermolecular-potential function which consists of a hard core and a square-plus-triangle well is proposed. The square width is taken to be lambda 1 -1 and the triangle width is lambda 2 -lambda 1 , where the diameter of the molecules is assumed to be epsilon. Under the restriction that the area under the potential well should be equal to 0.5epsilon, which has its own reason, it is shown that the appropriate choice of lambda 1 and lambda 2 that best mimics the Lennard-Jones (LJ) cut-off results is 1.15 and 1.85 respectively. With this choice for lambda 1 and lambda 2 , the proposed model is effective and satisfactory

  20. Dancoff Correction in Square and Hexagonal Lattices

    Energy Technology Data Exchange (ETDEWEB)

    Carlvik, I

    1966-11-15

    This report presents the results of a series of calculations of Dancoff corrections for square and hexagonal rod lattices. The tables cover a wide range of volume ratios and moderator cross sections. The results were utilized for checking the approximative formula of Sauer and also the modification of Bonalumi to Sauer's formula. The modified formula calculates the Dancoff correction with an accuracy of 0.01 - 0.02 in cases of practical interest. Calculations have also been performed on square lattices with an empty gap surrounding the rods. The results demonstrate the error involved in treating this kind of geometry by means of homogenizing the gap and the moderator. The calculations were made on the Ferranti Mercury computer of AB Atomenergi before it was closed down. Since then FORTRAN routines for Dancoff corrections have been written, and a subroutine DASQHE is included in the report.

  1. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai; Schuster, Gerard T.

    2016-01-01

    Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

  2. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai

    2016-09-06

    Elastic least-squares reverse time migration (LSRTM) is used to invert synthetic particle-velocity data and crosswell pressure field data. The migration images consist of both the P- and Svelocity perturbation images. Numerical tests on synthetic and field data illustrate the advantages of elastic LSRTM over elastic reverse time migration (RTM). In addition, elastic LSRTM images are better focused and have better reflector continuity than do the acoustic LSRTM images.

  3. Natural convective heat transfer from square cylinder

    Energy Technology Data Exchange (ETDEWEB)

    Novomestský, Marcel, E-mail: marcel.novomestsky@fstroj.uniza.sk; Smatanová, Helena, E-mail: helena.smatanova@fstroj.uniza.sk; Kapjor, Andrej, E-mail: andrej.kapjor@fstroj.uniza.sk [University of Žilina, Faculty of Mechanical Engineering, Department of Power Engineering, Univerzitná 1, 010 26 Žilina (Slovakia)

    2016-06-30

    This article is concerned with natural convective heat transfer from square cylinder mounted on a plane adiabatic base, the cylinders having an exposed cylinder surface according to different horizontal angle. The cylinder receives heat from a radiating heater which results in a buoyant flow. There are many industrial applications, including refrigeration, ventilation and the cooling of electrical components, for which the present study may be applicable.

  4. Least Squares Problems with Absolute Quadratic Constraints

    Directory of Open Access Journals (Sweden)

    R. Schöne

    2012-01-01

    Full Text Available This paper analyzes linear least squares problems with absolute quadratic constraints. We develop a generalized theory following Bookstein's conic-fitting and Fitzgibbon's direct ellipse-specific fitting. Under simple preconditions, it can be shown that a minimum always exists and can be determined by a generalized eigenvalue problem. This problem is numerically reduced to an eigenvalue problem by multiplications of Givens' rotations. Finally, four applications of this approach are presented.

  5. A least-squares computational ''tool kit''

    International Nuclear Information System (INIS)

    Smith, D.L.

    1993-04-01

    The information assembled in this report is intended to offer a useful computational ''tool kit'' to individuals who are interested in a variety of practical applications for the least-squares method of parameter estimation. The fundamental principles of Bayesian analysis are outlined first and these are applied to development of both the simple and the generalized least-squares conditions. Formal solutions that satisfy these conditions are given subsequently. Their application to both linear and non-linear problems is described in detail. Numerical procedures required to implement these formal solutions are discussed and two utility computer algorithms are offered for this purpose (codes LSIOD and GLSIOD written in FORTRAN). Some simple, easily understood examples are included to illustrate the use of these algorithms. Several related topics are then addressed, including the generation of covariance matrices, the role of iteration in applications of least-squares procedures, the effects of numerical precision and an approach that can be pursued in developing data analysis packages that are directed toward special applications

  6. Advancing Astrophysics with the Square Kilometre Array

    CERN Document Server

    Fender, Rob; Govoni, Federica; Green, Jimi; Hoare, Melvin; Jarvis, Matt; Johnston-Hollitt, Melanie; Keane, Evan; Koopmans, Leon; Kramer, Michael; Maartens, Roy; Macquart, Jean-Pierre; Mellema, Garrelt; Oosterloo, Tom; Prandoni, Isabella; Pritchard, Jonathan; Santos, Mario; Seymour, Nick; Stappers, Ben; Staveley-Smith, Lister; Tian, Wen Wu; Umana, Grazia; Wagg, Jeff; Bourke, Tyler L; AASKA14

    2015-01-01

    In 2014 it was 10 years since the publication of the comprehensive ‘Science with the Square Kilometre Array’ book and 15 years since the first such volume appeared in 1999. In that time numerous and unexpected advances have been made in the fields of astronomy and physics relevant to the capabilities of the Square Kilometre Array (SKA). The SKA itself progressed from an idea to a developing reality with a baselined Phase 1 design (SKA1) and construction planned from 2017. To facilitate the publication of a new, updated science book, which will be relevant to the current astrophysical context, the meeting "Advancing Astrophysics with the Square Kilometre Array" was held in Giardina Naxos, Sicily. Articles were solicited from the community for that meeting to document the scientific advances enabled by the first phase of the SKA and those pertaining to future SKA deployments, with expected gains of 5 times the Phase 1 sensitivity below 350 MHz, about 10 times the Phase 1 sensitivity above 350 MHz and with f...

  7. Dividing Streamline Formation Channel Confluences by Physical Modeling

    Directory of Open Access Journals (Sweden)

    Minarni Nur Trilita

    2010-02-01

    Full Text Available Confluence channels are often found in open channel network system and is the most important element. The incoming flow from the branch channel to the main cause various forms and cause vortex flow. Phenomenon can cause erosion of the side wall of the channel, the bed channel scour and sedimentation in the downstream confluence channel. To control these problems needed research into the current width of the branch channel. The incoming flow from the branch channel to the main channel flow bounded by a line distributors (dividing streamline. In this paper, the wide dividing streamline observed in the laboratory using a physical model of two open channels, a square that formed an angle of 30º. Observations were made with a variety of flow coming from each channel. The results obtained in the laboratory observation that the width of dividing streamline flow is influenced by the discharge ratio between the channel branch with the main channel. While the results of a comparison with previous studies showing that the observation in the laboratory is smaller than the results of previous research.

  8. XAFS study of copper(II) complexes with square planar and square pyramidal coordination geometries

    Science.gov (United States)

    Gaur, A.; Klysubun, W.; Nitin Nair, N.; Shrivastava, B. D.; Prasad, J.; Srivastava, K.

    2016-08-01

    X-ray absorption fine structure of six Cu(II) complexes, Cu2(Clna)4 2H2O (1), Cu2(ac)4 2H2O (2), Cu2(phac)4 (pyz) (3), Cu2(bpy)2(na)2 H2O (ClO4) (4), Cu2(teen)4(OH)2(ClO4)2 (5) and Cu2(tmen)4(OH)2(ClO4)2 (6) (where ac, phac, pyz, bpy, na, teen, tmen = acetate, phenyl acetate, pyrazole, bipyridine, nicotinic acid, tetraethyethylenediamine, tetramethylethylenediamine, respectively), which were supposed to have square pyramidal and square planar coordination geometries have been investigated. The differences observed in the X-ray absorption near edge structure (XANES) features of the standard compounds having four, five and six coordination geometry points towards presence of square planar and square pyramidal geometry around Cu centre in the studied complexes. The presence of intense pre-edge feature in the spectra of four complexes, 1-4, indicates square pyramidal coordination. Another important XANES feature, present in complexes 5 and 6, is prominent shoulder in the rising part of edge whose intensity decreases in the presence of axial ligands and thus indicates four coordination in these complexes. Ab initio calculations were carried out for square planar and square pyramidal Cu centres to observe the variation of 4p density of states in the presence and absence of axial ligands. To determine the number and distance of scattering atoms around Cu centre in the complexes, EXAFS analysis has been done using the paths obtained from Cu(II) oxide model and an axial Cu-O path from model of a square pyramidal complex. The results obtained from EXAFS analysis have been reported which confirmed the inference drawn from XANES features. Thus, it has been shown that these paths from model of a standard compound can be used to determine the structural parameters for complexes having unknown structure.

  9. Lax-pair operators for squared-sum and squared-difference eigenfunctions

    International Nuclear Information System (INIS)

    Ichikawa, Yoshihiko; Iino, Kazuhiro.

    1984-10-01

    Inter-relationship between various representations of the inverse scattering transformation is established by examining eigenfunctions of Lax-pair operators of the sine-Gordon equation and the modified Korteweg-de Vries equation. In particular, it is shown explicitly that there exists Lax-pair operators for the squared-sum and squared-difference eigenfunctions of the Ablowitz-Kaup-Newell-Segur inverse scattering transformation. (author)

  10. Robust Transceiver Design for Multiuser MIMO Downlink with Channel Uncertainties

    Science.gov (United States)

    Miao, Wei; Li, Yunzhou; Chen, Xiang; Zhou, Shidong; Wang, Jing

    This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.

  11. Citizens and service channels: channel choice and channel management implications

    NARCIS (Netherlands)

    Pieterson, Willem Jan

    2010-01-01

    The arrival of electronic channels in the 1990s has had a huge impact on governmental service delivery. The new channels have led to many new opportunities to improve public service delivery, not only in terms of citizen satisfaction, but also in cost reduction for governmental agencies. However,

  12. Local Transfer Coefficient, Smooth Channel

    Directory of Open Access Journals (Sweden)

    R. T. Kukreja

    1998-01-01

    Full Text Available Naphthalene sublimation technique and the heat/mass transfer analogy are used to determine the detailed local heat/mass transfer distributions on the leading and trailing walls of a twopass square channel with smooth walls that rotates about a perpendicular axis. Since the variation of density is small in the flow through the channel, buoyancy effect is negligible. Results show that, in both the stationary and rotating channel cases, very large spanwise variations of the mass transfer exist in he turn and in the region immediately downstream of the turn in the second straight pass. In the first straight pass, the rotation-induced Coriolis forces reduce the mass transfer on the leading wall and increase the mass transfer on the trailing wall. In the turn, rotation significantly increases the mass transfer on the leading wall, especially in the upstream half of the turn. Rotation also increases the mass transfer on the trailing wall, more in the downstream half of the turn than in the upstream half of the turn. Immediately downstream of the turn, rotation causes the mass transfer to be much higher on the trailing wall near the downstream corner of the tip of the inner wall than on the opposite leading wall. The mass transfer in the second pass is higher on the leading wall than on the trailing wall. A slower flow causes higher mass transfer enhancement in the turn on both the leading and trailing walls.

  13. Leonardo Pisano (Fibonacci) the book of squares

    CERN Document Server

    Sigler, L E

    1987-01-01

    The Book of Squares by Fibonacci is a gem in the mathematical literature and one of the most important mathematical treatises written in the Middle Ages. It is a collection of theorems on indeterminate analysis and equations of second degree which yield, among other results, a solution to a problem proposed by Master John of Palermo to Leonardo at the Court of Frederick II. The book was dedicated and presented to the Emperor at Pisa in 1225. Dating back to the 13th century the book exhibits the early and continued fascination of men with our number system and the relationship among numbers

  14. Least Squares Methods for Equidistant Tree Reconstruction

    OpenAIRE

    Fahey, Conor; Hosten, Serkan; Krieger, Nathan; Timpe, Leslie

    2008-01-01

    UPGMA is a heuristic method identifying the least squares equidistant phylogenetic tree given empirical distance data among $n$ taxa. We study this classic algorithm using the geometry of the space of all equidistant trees with $n$ leaves, also known as the Bergman complex of the graphical matroid for the complete graph $K_n$. We show that UPGMA performs an orthogonal projection of the data onto a maximal cell of the Bergman complex. We also show that the equidistant tree with the least (Eucl...

  15. Magnetics calculations for an ELMO Bumpy square

    International Nuclear Information System (INIS)

    Santoro, R.T.; Uckan, N.A.; Schmidt, R.J.

    1985-01-01

    Advanced ELMO Bumpy Torus (EBT) concepts have been studied in an effort to determine the potential for new and different concepts as confinement experiments or as reactors. Several magnetic configurations based on the EBT confinement concept were developed including the ELMO Bumpy Square (EBS). The EBS was selected as a possible candidate for near-term study because of its potential for resolving critical EBT issues, for its desirability as a reactor, and for anticipated contributions to the physics and technology of fusion. This paper summarizes magnetics calculations that were carried out in support of studies to assess the merits of an EBS

  16. Computational logic with square rings of nanomagnets

    Science.gov (United States)

    Arava, Hanu; Derlet, Peter M.; Vijayakumar, Jaianth; Cui, Jizhai; Bingham, Nicholas S.; Kleibert, Armin; Heyderman, Laura J.

    2018-06-01

    Nanomagnets are a promising low-power alternative to traditional computing. However, the successful implementation of nanomagnets in logic gates has been hindered so far by a lack of reliability. Here, we present a novel design with dipolar-coupled nanomagnets arranged on a square lattice to (i) support transfer of information and (ii) perform logic operations. We introduce a thermal protocol, using thermally active nanomagnets as a means to perform computation. Within this scheme, the nanomagnets are initialized by a global magnetic field and thermally relax on raising the temperature with a resistive heater. We demonstrate error-free transfer of information in chains of up to 19 square rings and we show a high level of reliability with successful gate operations of ∼94% across more than 2000 logic gates. Finally, we present a functionally complete prototype NAND/NOR logic gate that could be implemented for advanced logic operations. Here we support our experiments with simulations of the thermally averaged output and determine the optimal gate parameters. Our approach provides a new pathway to a long standing problem concerning reliability in the use of nanomagnets for computation.

  17. Mixed convection heat transfer from confined tandem square cylinders in a horizontal channel

    KAUST Repository

    Huang, Zhu; Xi, Guang; Zhang, Wei; Wen, Suping

    2013-01-01

    with four widths of the cylinder and the blockage ratio and the Prandtl number are fixed at 0.1 and 0.7 respectively. The mixed convective flow and heat transfer is simulated by high accuracy multidomain pseudospectral method. The Reynolds number (Re

  18. Magnitude Squared of Coherence to Detect Imaginary Movement

    Directory of Open Access Journals (Sweden)

    Sady Antônio Santos Filho

    2009-01-01

    Full Text Available This work investigates the Magnitude Squared of Coherence (MSC for detection of Event Related Potentials (ERPs related to left-hand index finger movement. Initially, ERP presence was examined in different brain areas. To accomplish that, 20 EEG channels were used, positioned according to the 10–20 international system. The grand average, resulting from 10 normal subjects showed, as expected, responses at frontal, central, and parietal areas, particularly evident at the central area (C3, C4, Cz. The MSC, applied to movement imagination related EEG signals, detected a consistent response in frequencies around 0.3–1 Hz (delta band, mainly at central area (C3, Cz, and C4. Ability differences in control imagination among subjects produced different detection performance. Some subjects needed up to 45 events for a detectable response, while for some others only 10 events proved sufficient. Some subjects also required two or three experimental sessions in order to achieve detectable responses. For one subject, response detection was not possible at all. However, due to brain plasticity, it is plausible to expect that training sessions (to practice movement imagination improve signal-noise ratio and lead to better detection using MSC. Results are sufficiently encouraging as to suggest further exploration of MSC for future BCI application.

  19. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Haibing Yang

    2007-05-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a K-factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  20. Channel Characteristics and Transmission Performance for Various Channel Configurations at 60 GHz

    Directory of Open Access Journals (Sweden)

    Yang Haibing

    2007-01-01

    Full Text Available Extensive measurements are conducted in room environments at 60 GHz to analyze the channel characteristics for various channel configurations. Channel parameters retrieved from measurements are presented and analyzed based on generic channel models. Particularly, a simple single-cluster model is applied for the parameter retrieval and performance evaluation. By this model, power delay profiles are simply described by a -factor, a root-mean-squared delay spread, and a shape parameter. The considered channels are configured with the combination of omnidirectional, fan-beam, and pencil-beam antennas at transmitter and receiver sides. Both line-of-sight (LOS and non-LOS (NLOS channels are considered. Further, to evaluate the transmission performance, we analyze the link budget in the considered environments, then design and simulate an OFDM system with a data rate of 2 Gbps to compare the bit-error-rate (BER performance by using the measured and modeled channels. Both coded and uncoded OFDM systems are simulated. It is observed that the BER performance agrees well for the measured and modeled channels. In addition, directive configurations can provide sufficient link margins and BER performance for high data rate communications. To increase the coverage and performance in the NLOS area, it is preferable to apply directive antennas.

  1. Vapor-liquid equilibrium and critical asymmetry of square well and short square well chain fluids.

    Science.gov (United States)

    Li, Liyan; Sun, Fangfang; Chen, Zhitong; Wang, Long; Cai, Jun

    2014-08-07

    The critical behavior of square well fluids with variable interaction ranges and of short square well chain fluids have been investigated by grand canonical ensemble Monte Carlo simulations. The critical temperatures and densities were estimated by a finite-size scaling analysis with the help of histogram reweighting technique. The vapor-liquid coexistence curve in the near-critical region was determined using hyper-parallel tempering Monte Carlo simulations. The simulation results for coexistence diameters show that the contribution of |t|(1-α) to the coexistence diameter dominates the singular behavior in all systems investigated. The contribution of |t|(2β) to the coexistence diameter is larger for the system with a smaller interaction range λ. While for short square well chain fluids, longer the chain length, larger the contribution of |t|(2β). The molecular configuration greatly influences the critical asymmetry: a short soft chain fluid shows weaker critical asymmetry than a stiff chain fluid with same chain length.

  2. Simplified neural networks for solving linear least squares and total least squares problems in real time.

    Science.gov (United States)

    Cichocki, A; Unbehauen, R

    1994-01-01

    In this paper a new class of simplified low-cost analog artificial neural networks with on chip adaptive learning algorithms are proposed for solving linear systems of algebraic equations in real time. The proposed learning algorithms for linear least squares (LS), total least squares (TLS) and data least squares (DLS) problems can be considered as modifications and extensions of well known algorithms: the row-action projection-Kaczmarz algorithm and/or the LMS (Adaline) Widrow-Hoff algorithms. The algorithms can be applied to any problem which can be formulated as a linear regression problem. The correctness and high performance of the proposed neural networks are illustrated by extensive computer simulation results.

  3. A Fast LMMSE Channel Estimation Method for OFDM Systems

    Directory of Open Access Journals (Sweden)

    Zhou Wen

    2009-01-01

    Full Text Available A fast linear minimum mean square error (LMMSE channel estimation method has been proposed for Orthogonal Frequency Division Multiplexing (OFDM systems. In comparison with the conventional LMMSE channel estimation, the proposed channel estimation method does not require the statistic knowledge of the channel in advance and avoids the inverse operation of a large dimension matrix by using the fast Fourier transform (FFT operation. Therefore, the computational complexity can be reduced significantly. The normalized mean square errors (NMSEs of the proposed method and the conventional LMMSE estimation have been derived. Numerical results show that the NMSE of the proposed method is very close to that of the conventional LMMSE method, which is also verified by computer simulation. In addition, computer simulation shows that the performance of the proposed method is almost the same with that of the conventional LMMSE method in terms of bit error rate (BER.

  4. Quantum mechanical streamlines. I - Square potential barrier

    Science.gov (United States)

    Hirschfelder, J. O.; Christoph, A. C.; Palke, W. E.

    1974-01-01

    Exact numerical calculations are made for scattering of quantum mechanical particles hitting a square two-dimensional potential barrier (an exact analog of the Goos-Haenchen optical experiments). Quantum mechanical streamlines are plotted and found to be smooth and continuous, to have continuous first derivatives even through the classical forbidden region, and to form quantized vortices around each of the nodal points. A comparison is made between the present numerical calculations and the stationary wave approximation, and good agreement is found between both the Goos-Haenchen shifts and the reflection coefficients. The time-independent Schroedinger equation for real wavefunctions is reduced to solving a nonlinear first-order partial differential equation, leading to a generalization of the Prager-Hirschfelder perturbation scheme. Implications of the hydrodynamical formulation of quantum mechanics are discussed, and cases are cited where quantum and classical mechanical motions are identical.

  5. Square well approximation to the optical potential

    International Nuclear Information System (INIS)

    Jain, A.K.; Gupta, M.C.; Marwadi, P.R.

    1976-01-01

    Approximations for obtaining T-matrix elements for a sum of several potentials in terms of T-matrices for individual potentials are studied. Based on model calculations for S-wave for a sum of two separable non-local potentials of Yukawa type form factors and a sum of two delta function potentials, it is shown that the T-matrix for a sum of several potentials can be approximated satisfactorily over all the energy regions by the sum of T-matrices for individual potentials. Based on this, an approximate method for finding T-matrix for any local potential by approximating it by a sum of suitable number of square wells is presented. This provides an interesting way to calculate the T-matrix for any arbitary potential in terms of Bessel functions to a good degree of accuracy. The method is applied to the Saxon-Wood potentials and good agreement with exact results is found. (author)

  6. ANYOLS, Least Square Fit by Stepwise Regression

    International Nuclear Information System (INIS)

    Atwoods, C.L.; Mathews, S.

    1986-01-01

    Description of program or function: ANYOLS is a stepwise program which fits data using ordinary or weighted least squares. Variables are selected for the model in a stepwise way based on a user- specified input criterion or a user-written subroutine. The order in which variables are entered can be influenced by user-defined forcing priorities. Instead of stepwise selection, ANYOLS can try all possible combinations of any desired subset of the variables. Automatic output for the final model in a stepwise search includes plots of the residuals, 'studentized' residuals, and leverages; if the model is not too large, the output also includes partial regression and partial leverage plots. A data set may be re-used so that several selection criteria can be tried. Flexibility is increased by allowing the substitution of user-written subroutines for several default subroutines

  7. Optimally weighted least-squares steganalysis

    Science.gov (United States)

    Ker, Andrew D.

    2007-02-01

    Quantitative steganalysis aims to estimate the amount of payload in a stego object, and such estimators seem to arise naturally in steganalysis of Least Significant Bit (LSB) replacement in digital images. However, as with all steganalysis, the estimators are subject to errors, and their magnitude seems heavily dependent on properties of the cover. In very recent work we have given the first derivation of estimation error, for a certain method of steganalysis (the Least-Squares variant of Sample Pairs Analysis) of LSB replacement steganography in digital images. In this paper we make use of our theoretical results to find an improved estimator and detector. We also extend the theoretical analysis to another (more accurate) steganalysis estimator (Triples Analysis) and hence derive an improved version of that estimator too. Experimental results show that the new steganalyzers have improved accuracy, particularly in the difficult case of never-compressed covers.

  8. The Square Kilometre Array: An Engineering Perspective

    CERN Document Server

    Hall, Peter J

    2005-01-01

    This volume is an up-to-date and comprehensive overview of the engineering of the Square Kilometre Array (SKA), a revolutionary instrument which will be the world’s largest radio telescope. Expected to be completed by 2020, the SKA will be a pre-eminent tool in probing the Early Universe and in enhancing greatly the discovery potential of radio astronomy in many other fields. This book, containing 36 refereed papers written by leaders in SKA engineering, has been compiled by the International SKA Project Office and is the only contemporary compendium available. It features papers dealing with pivotal technologies such as antennas, RF systems and data transport. As well, overviews of important SKA demonstrator instruments and key system design issues are included. Practising professionals, and students interested in next-generation telescopes, will find this book an invaluable reference.

  9. Least square regularized regression in sum space.

    Science.gov (United States)

    Xu, Yong-Li; Chen, Di-Rong; Li, Han-Xiong; Liu, Lu

    2013-04-01

    This paper proposes a least square regularized regression algorithm in sum space of reproducing kernel Hilbert spaces (RKHSs) for nonflat function approximation, and obtains the solution of the algorithm by solving a system of linear equations. This algorithm can approximate the low- and high-frequency component of the target function with large and small scale kernels, respectively. The convergence and learning rate are analyzed. We measure the complexity of the sum space by its covering number and demonstrate that the covering number can be bounded by the product of the covering numbers of basic RKHSs. For sum space of RKHSs with Gaussian kernels, by choosing appropriate parameters, we tradeoff the sample error and regularization error, and obtain a polynomial learning rate, which is better than that in any single RKHS. The utility of this method is illustrated with two simulated data sets and five real-life databases.

  10. Multiples least-squares reverse time migration

    KAUST Repository

    Zhang, Dongliang

    2013-01-01

    To enhance the image quality, we propose multiples least-squares reverse time migration (MLSRTM) that transforms each hydrophone into a virtual point source with a time history equal to that of the recorded data. Since each recorded trace is treated as a virtual source, knowledge of the source wavelet is not required. Numerical tests on synthetic data for the Sigsbee2B model and field data from Gulf of Mexico show that MLSRTM can improve the image quality by removing artifacts, balancing amplitudes, and suppressing crosstalk compared to standard migration of the free-surface multiples. The potential liability of this method is that multiples require several roundtrips between the reflector and the free surface, so that high frequencies in the multiples are attenuated compared to the primary reflections. This can lead to lower resolution in the migration image compared to that computed from primaries.

  11. Tensor hypercontraction. II. Least-squares renormalization

    Science.gov (United States)

    Parrish, Robert M.; Hohenstein, Edward G.; Martínez, Todd J.; Sherrill, C. David

    2012-12-01

    The least-squares tensor hypercontraction (LS-THC) representation for the electron repulsion integral (ERI) tensor is presented. Recently, we developed the generic tensor hypercontraction (THC) ansatz, which represents the fourth-order ERI tensor as a product of five second-order tensors [E. G. Hohenstein, R. M. Parrish, and T. J. Martínez, J. Chem. Phys. 137, 044103 (2012)], 10.1063/1.4732310. Our initial algorithm for the generation of the THC factors involved a two-sided invocation of overlap-metric density fitting, followed by a PARAFAC decomposition, and is denoted PARAFAC tensor hypercontraction (PF-THC). LS-THC supersedes PF-THC by producing the THC factors through a least-squares renormalization of a spatial quadrature over the otherwise singular 1/r12 operator. Remarkably, an analytical and simple formula for the LS-THC factors exists. Using this formula, the factors may be generated with O(N^5) effort if exact integrals are decomposed, or O(N^4) effort if the decomposition is applied to density-fitted integrals, using any choice of density fitting metric. The accuracy of LS-THC is explored for a range of systems using both conventional and density-fitted integrals in the context of MP2. The grid fitting error is found to be negligible even for extremely sparse spatial quadrature grids. For the case of density-fitted integrals, the additional error incurred by the grid fitting step is generally markedly smaller than the underlying Coulomb-metric density fitting error. The present results, coupled with our previously published factorizations of MP2 and MP3, provide an efficient, robust O(N^4) approach to both methods. Moreover, LS-THC is generally applicable to many other methods in quantum chemistry.

  12. Fuel assembly and fuel channel box

    International Nuclear Information System (INIS)

    Sakuma, Toraki; Hirakawa, Hiromasa; Ishizaki, Hideaki; Nakajima, Junjiro; Aizawa, Yasuhiro.

    1992-01-01

    A fuel channel box has a square cylindrical shape and, in the transversal cross sectional shape, the wall thickness of a corner portion is greater than that of a central portion of the side wall except for an upper portion thereof. The upper portion of the channel box includes a region to be in contact with an upper lattice plate and a region to attach a channel spacer. Then, the wall thickness of these regions is uniform in the transversal cross section and they have the same wall thickness with that of the corner portion which has the increased wall thickness. With such a constitution, the upper portion of the channel box receives a counter force applied from the upper lattice plate upon occurrence of earthquakes and moderate it to reduce local stresses and deformation. Further, a similar region with increased wall thickness is disposed also to the lower portion of the channel box, thereby enabling to suppress the amount of coolants leaked from a portion between the lower portion and a lower tie plate, and improve the mechanical integrity of the channel box. (I.N.)

  13. Test of the Bank Lending Channel: The Case of Poland

    Directory of Open Access Journals (Sweden)

    Yu HSING

    2013-11-01

    Full Text Available This paper tests the bank lending channel for Poland based on a simultaneousequation model consisting of demand for and supply of bank loans. The three-stage least squares method is employed in empirical work. This paper finds support for a bank lending channel for Poland. Expansionary monetary policy through a lower money market rate or open market purchase of government bonds to increase bank reserves/deposits would increase bank loan supply.

  14. 2010 U.S. Geological Survey (USGS) Topographic Lidar: Channel Islands, California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Terrapoint collected LiDAR for 197 square miles covering five islands off the coast of Los Angeles, California. These islands are part of the Channel Islands...

  15. A pilot study of treatment of striae distensae with variable square pulse Erbium: YAG laser resurfacing.

    Science.gov (United States)

    Wanitphakdeedecha, Rungsima; Meeprathom, Walailak; Manuskiatti, Woraphong

    2017-12-01

    Striae distensae (SD) are a frequent skin condition for which treatment remains a challenge. Various laser treatments have been employed to remove the epidermis and cause dermal wound and heating with subsequent dermal collagen remodeling. To determine the efficacy and safety of a variable square pulse Erbium: YAG (VSP Er:YAG) laser for the treatment of striae in skin phototypes III-IV. Twenty-one women with SD were treated monthly for 2 months with VSP Er:YAG laser resurfacing using a 7-mm spot size. One side of their striae was randomly treated with one pass of 400 mJ in short pulse (SP) mode with 50% overlapping and one pass of 2.2 J/cm 2 in smooth (SM) mode with nonoverlapping. The other side of their striae was treated with two passes of 400 mJ in SP mode with 50% overlapping. Objective and subjective assessments were obtained at baseline and 1-, 3-, and 6-month after treatment. In both SP&SM and SP only group, volume of SD measured by Visioscan VC98 reduced significantly at 6-month follow-up visit (P=.017 and P=.034, respectively). There were no statistically significant differences in skin roughness (SER), skin smoothness (SESM), and surface measured by Visioscan VC98. Transient postinflammatory hyperpigmentation (PIH) is the common side effect found in patients with darker skin tone even in nonsun exposure areas and can last as long as 6 months. VSP Er:YAG laser resurfacing is a promising treatment option for SD. Lower fluence should be used in patients with darker skin phototype to avoid the risk of PIH. In addition, pre- and post-treatment with topical preparations for PIH prevention may be needed. © 2017 Wiley Periodicals, Inc.

  16. On the capacity of nakagami-m fading Channels with full channel state information at low SNR

    KAUST Repository

    Rezki, Zouheir

    2012-06-01

    The capacity of flat Rayleigh fading channels with full channel state information (CSI) at the transmitter and at the receiver at asymptotically low SNR has been recently shown to scale essentially as SNR log(1/SNR)}. In this paper, we investigate the Nakagami-m fading channel capacity with full CSI, and show that the capacity of this channel scales essentially as m/ Omega SNR log(1/SNR), where m is the Nakagami-m fading parameter and where Ω is the channel mean-square. We also show that one-bit CSI at the transmitter is enough to achieve this asymptotic capacity using an On-Off power control scheme. Our framework may be seen as a generalization of previous works as it captures the Rayleigh fading channel as a special case by taking m=1. © 2012 IEEE.

  17. Multiplier less high-speed squaring circuit for binary numbers

    Science.gov (United States)

    Sethi, Kabiraj; Panda, Rutuparna

    2015-03-01

    The squaring operation is important in many applications in signal processing, cryptography etc. In general, squaring circuits reported in the literature use fast multipliers. A novel idea of a squaring circuit without using multipliers is proposed in this paper. Ancient Indian method used for squaring decimal numbers is extended here for binary numbers. The key to our success is that no multiplier is used. Instead, one squaring circuit is used. The hardware architecture of the proposed squaring circuit is presented. The design is coded in VHDL and synthesised and simulated in Xilinx ISE Design Suite 10.1 (Xilinx Inc., San Jose, CA, USA). It is implemented in Xilinx Vertex 4vls15sf363-12 device (Xilinx Inc.). The results in terms of time delay and area is compared with both modified Booth's algorithm and squaring circuit using Vedic multipliers. Our proposed squaring circuit seems to have better performance in terms of both speed and area.

  18. Evaluating Outlier Identification Tests: Mahalanobis "D" Squared and Comrey "Dk."

    Science.gov (United States)

    Rasmussen, Jeffrey Lee

    1988-01-01

    A Monte Carlo simulation was used to compare the Mahalanobis "D" Squared and the Comrey "Dk" methods of detecting outliers in data sets. Under the conditions investigated, the "D" Squared technique was preferable as an outlier removal statistic. (SLD)

  19. USACE Navigation Channels 2012

    Data.gov (United States)

    California Natural Resource Agency — This dataset represents both San Francisco and Los Angeles District navigation channel lines. All San Francisco District channel lines were digitized from CAD files...

  20. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used ...

  1. Testing the gravitational inverse-square law

    International Nuclear Information System (INIS)

    Adelberger, Eric; Heckel, B.; Hoyle, C.D.

    2005-01-01

    If the universe contains more than three spatial dimensions, as many physicists believe, our current laws of gravity should break down at small distances. When Isaac Newton realized that the acceleration of the Moon as it orbited around the Earth could be related to the acceleration of an apple as it fell to the ground, it was the first time that two seemingly unrelated physical phenomena had been 'unified'. The quest to unify all the forces of nature is one that still keeps physicists busy today. Newton showed that the gravitational attraction between two point bodies is proportional to the product of their masses and inversely proportional to the square of the distance between them. Newton's theory, which assumes that the gravitational force acts instantaneously, remained essentially unchallenged for roughly two centuries until Einstein proposed the general theory of relativity in 1915. Einstein's radical new theory made gravity consistent with the two basic ideas of relativity: the world is 4D - the three directions of space combined with time - and no physical effect can travel faster than light. The theory of general relativity states that gravity is not a force in the usual sense but a consequence of the curvature of this space-time produced by mass or energy. However, in the limit of low velocities and weak gravitational fields, Einstein's theory still predicts that the gravitational force between two point objects obeys an inverse-square law. One of the outstanding challenges in physics is to finish what Newton started and achieve the ultimate 'grand unification' - to unify gravity with the other three fundamental forces (the electromagnetic force, and the strong and weak nuclear forces) into a single quantum theory. In string theory - one of the leading candidates for an ultimate theory - the fundamental entities of nature are 1D strings and higher-dimensional objects called 'branes', rather than the point-like particles we are familiar with. String

  2. Multisource Least-squares Reverse Time Migration

    KAUST Repository

    Dai, Wei

    2012-12-01

    Least-squares migration has been shown to be able to produce high quality migration images, but its computational cost is considered to be too high for practical imaging. In this dissertation, a multisource least-squares reverse time migration algorithm (LSRTM) is proposed to increase by up to 10 times the computational efficiency by utilizing the blended sources processing technique. There are three main chapters in this dissertation. In Chapter 2, the multisource LSRTM algorithm is implemented with random time-shift and random source polarity encoding functions. Numerical tests on the 2D HESS VTI data show that the multisource LSRTM algorithm suppresses migration artifacts, balances the amplitudes, improves image resolution, and reduces crosstalk noise associated with the blended shot gathers. For this example, multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution, and fewer migration artifacts compared to conventional RTM. The empirical results suggest that the multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with similar or less computational cost. The caveat is that LSRTM image is sensitive to large errors in the migration velocity model. In Chapter 3, the multisource LSRTM algorithm is implemented with frequency selection encoding strategy and applied to marine streamer data, for which traditional random encoding functions are not applicable. The frequency-selection encoding functions are delta functions in the frequency domain, so that all the encoded shots have unique non-overlapping frequency content. Therefore, the receivers can distinguish the wavefield from each shot according to the frequencies. With the frequency-selection encoding method, the computational efficiency of LSRTM is increased so that its cost is

  3. Quantum Channels With Memory

    International Nuclear Information System (INIS)

    Rybar, T.

    2012-01-01

    Quantum memory channels represent a very general, yet simple and comprehensible model for causal processes. As such they have attracted considerable research interest, mostly aimed on their transfer capabilities and structure properties. Most notably it was shown that memory channels can be implemented via physically naturally motivated collision models. We also define the concept of repeatable channels and show that only unital channels can be implemented repeat ably with pure memory channels. In the special case of qubit channels we also show that every unital qubit channel has a repeatable implementation. We also briefly explore the possibilities of stroboscopical simulation of channels and show that all random unitary channels can be stroboscopically simulated. Particularly in qubit case, all indivisible qubit channels are also random unitary, hence for qubit all indivisible channels can be stroboscopically simulated. Memory channels also naturally capture the framework of correlated experiments. We develop methods to gather and interpret data obtained in such setting and in detail examine the two qubit case. We also show that for control unitary interactions the measured data will never contradict a simple unitary evolution. Thus no memory effects can be spotted then. (author)

  4. Eight channel fast scalar

    Energy Technology Data Exchange (ETDEWEB)

    Waddoup, W D; Stubbs, R J [Durham Univ. (UK)

    1977-11-01

    An eight channel 64-bit scaler has been constructed with a static CMOS memory. Scaling frequencies are independently variable, at each channel, as are the number of bits/channel. The scaler, when used in conjunction with a multichannel charge to time converter results in a very flexible, gated multichannel ADC.

  5. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

    2014-01-01

    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  6. Delayed ripple counter simplifies square-root computation

    Science.gov (United States)

    Cliff, R.

    1965-01-01

    Ripple subtract technique simplifies the logic circuitry required in a binary computing device to derive the square root of a number. Successively higher numbers are subtracted from a register containing the number out of which the square root is to be extracted. The last number subtracted will be the closest integer to the square root of the number.

  7. Skeletonized Least Squares Wave Equation Migration

    KAUST Repository

    Zhan, Ge

    2010-10-17

    The theory for skeletonized least squares wave equation migration (LSM) is presented. The key idea is, for an assumed velocity model, the source‐side Green\\'s function and the geophone‐side Green\\'s function are computed by a numerical solution of the wave equation. Only the early‐arrivals of these Green\\'s functions are saved and skeletonized to form the migration Green\\'s function (MGF) by convolution. Then the migration image is obtained by a dot product between the recorded shot gathers and the MGF for every trial image point. The key to an efficient implementation of iterative LSM is that at each conjugate gradient iteration, the MGF is reused and no new finitedifference (FD) simulations are needed to get the updated migration image. It is believed that this procedure combined with phase‐encoded multi‐source technology will allow for the efficient computation of wave equation LSM images in less time than that of conventional reverse time migration (RTM).

  8. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai

    2017-03-08

    We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

  9. Multilevel weighted least squares polynomial approximation

    KAUST Repository

    Haji-Ali, Abdul-Lateef

    2017-06-30

    Weighted least squares polynomial approximation uses random samples to determine projections of functions onto spaces of polynomials. It has been shown that, using an optimal distribution of sample locations, the number of samples required to achieve quasi-optimal approximation in a given polynomial subspace scales, up to a logarithmic factor, linearly in the dimension of this space. However, in many applications, the computation of samples includes a numerical discretization error. Thus, obtaining polynomial approximations with a single level method can become prohibitively expensive, as it requires a sufficiently large number of samples, each computed with a sufficiently small discretization error. As a solution to this problem, we propose a multilevel method that utilizes samples computed with different accuracies and is able to match the accuracy of single-level approximations with reduced computational cost. We derive complexity bounds under certain assumptions about polynomial approximability and sample work. Furthermore, we propose an adaptive algorithm for situations where such assumptions cannot be verified a priori. Finally, we provide an efficient algorithm for the sampling from optimal distributions and an analysis of computationally favorable alternative distributions. Numerical experiments underscore the practical applicability of our method.

  10. Elastic least-squares reverse time migration

    KAUST Repository

    Feng, Zongcai; Schuster, Gerard T.

    2017-01-01

    We use elastic least-squares reverse time migration (LSRTM) to invert for the reflectivity images of P- and S-wave impedances. Elastic LSRTMsolves the linearized elastic-wave equations for forward modeling and the adjoint equations for backpropagating the residual wavefield at each iteration. Numerical tests on synthetic data and field data reveal the advantages of elastic LSRTM over elastic reverse time migration (RTM) and acoustic LSRTM. For our examples, the elastic LSRTM images have better resolution and amplitude balancing, fewer artifacts, and less crosstalk compared with the elastic RTM images. The images are also better focused and have better reflector continuity for steeply dipping events compared to the acoustic LSRTM images. Similar to conventional leastsquares migration, elastic LSRTM also requires an accurate estimation of the P- and S-wave migration velocity models. However, the problem remains that, when there are moderate errors in the velocity model and strong multiples, LSRTMwill produce migration noise stronger than that seen in the RTM images.

  11. Phase transition in a modified square Josephson-junction array

    CERN Document Server

    Han, J

    1999-01-01

    We study the phase transition in a modified square proximity-coupled Josephson-junction array with small superconducting islands at the center of each plaquette. We find that the modified square array undergoes a Kosterlitz-Thouless-Berezinskii-like phase transition, but at a lower temperature than the simple square array with the same single-junction critical current. The IV characteristics, as well as the phase transition, resemble qualitatively those of a disordered simple square array. The effects of the presence of the center islands in the modified square array are discussed.

  12. Least Squares Estimate of the Initial Phases in STFT based Speech Enhancement

    DEFF Research Database (Denmark)

    Nørholm, Sidsel Marie; Krawczyk-Becker, Martin; Gerkmann, Timo

    2015-01-01

    In this paper, we consider single-channel speech enhancement in the short time Fourier transform (STFT) domain. We suggest to improve an STFT phase estimate by estimating the initial phases. The method is based on the harmonic model and a model for the phase evolution over time. The initial phases...... are estimated by setting up a least squares problem between the noisy phase and the model for phase evolution. Simulations on synthetic and speech signals show a decreased error on the phase when an estimate of the initial phase is included compared to using the noisy phase as an initialisation. The error...... on the phase is decreased at input SNRs from -10 to 10 dB. Reconstructing the signal using the clean amplitude, the mean squared error is decreased and the PESQ score is increased....

  13. Fine Channel Networks

    Science.gov (United States)

    1997-01-01

    A color image of fine channel networks on Mars; north toward top. The scene shows heavily cratered highlands dissected by dendritic open channel networks that dissect steep slopes of impact crater walls. This image is a composite of Viking high-resolution images in black and white and low-resolution images in color. The image extends from latitude 9 degrees S. to 5 degrees S. and from longitude 312 degrees to 320 degrees; Mercator projection. The dendritic pattern of the fine channels and their location on steep slopes leads to the interpretation that these are runoff channels. The restriction of these types of channels to ancient highland rocks suggests that these channels are old and date from a time on Mars when conditions existed for precipitation to actively erode rocks. After the channels reach a low plain, they appear to end. Termination may have resulted from burial by younger deposits or perhaps the flows percolated into the surface materials and continued underground.

  14. Ion channels in plants.

    Science.gov (United States)

    Hedrich, Rainer

    2012-10-01

    Since the first recordings of single potassium channel activities in the plasma membrane of guard cells more than 25 years ago, patch-clamp studies discovered a variety of ion channels in all cell types and plant species under inspection. Their properties differed in a cell type- and cell membrane-dependent manner. Guard cells, for which the existence of plant potassium channels was initially documented, advanced to a versatile model system for studying plant ion channel structure, function, and physiology. Interestingly, one of the first identified potassium-channel genes encoding the Shaker-type channel KAT1 was shown to be highly expressed in guard cells. KAT1-type channels from Arabidopsis thaliana and its homologs from other species were found to encode the K(+)-selective inward rectifiers that had already been recorded in early patch-clamp studies with guard cells. Within the genome era, additional Arabidopsis Shaker-type channels appeared. All nine members of the Arabidopsis Shaker family are localized at the plasma membrane, where they either operate as inward rectifiers, outward rectifiers, weak voltage-dependent channels, or electrically silent, but modulatory subunits. The vacuole membrane, in contrast, harbors a set of two-pore K(+) channels. Just very recently, two plant anion channel families of the SLAC/SLAH and ALMT/QUAC type were identified. SLAC1/SLAH3 and QUAC1 are expressed in guard cells and mediate Slow- and Rapid-type anion currents, respectively, that are involved in volume and turgor regulation. Anion channels in guard cells and other plant cells are key targets within often complex signaling networks. Here, the present knowledge is reviewed for the plant ion channel biology. Special emphasis is drawn to the molecular mechanisms of channel regulation, in the context of model systems and in the light of evolution.

  15. One photopeaks' analysis of gamma spectra for the minimum square method through one data processing system

    International Nuclear Information System (INIS)

    Baez Pedrajo, A.B.

    1974-01-01

    The essence of the work is a computer program by which the gamma spectrum of a radioisotope mixture can be analysed in accordance with a library of spectra for the elements assumed to make up the mixture. The program forms a linear combination of standards by the method of least linear squares, analyses the spectrum obtained with respect to the original, and applies to the results the criteria of mean value, variance, standard deviation, γ 2 and its quotient ratio, and the correlation coefficient. The program, written in Fortran, has no limitations as regards the number of channels for each spectrum or the number of spectra, provided all spectra are compatible (same number of channels). As the experimental part of the work a numerical example is given and analysed in critical form to evaluate the suitability of the computer program. (author)

  16. Compound Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Shlomo Shamai (Shitz

    2009-01-01

    Full Text Available This paper considers the compound wiretap channel, which generalizes Wyner's wiretap model to allow the channels to the (legitimate receiver and to the eavesdropper to take a number of possible states. No matter which states occur, the transmitter guarantees that the receiver decodes its message and that the eavesdropper is kept in full ignorance about the message. The compound wiretap channel can also be viewed as a multicast channel with multiple eavesdroppers, in which the transmitter sends information to all receivers and keeps the information secret from all eavesdroppers. For the discrete memoryless channel, lower and upper bounds on the secrecy capacity are derived. The secrecy capacity is established for the degraded channel and the semideterministic channel with one receiver. The parallel Gaussian channel is further studied. The secrecy capacity and the secrecy degree of freedom (s.d.o.f. are derived for the degraded case with one receiver. Schemes to achieve the s.d.o.f. for the case with two receivers and two eavesdroppers are constructed to demonstrate the necessity of a prefix channel in encoder design. Finally, the multi-antenna (i.e., MIMO compound wiretap channel is studied. The secrecy capacity is established for the degraded case and an achievable s.d.o.f. is given for the general case.

  17. Compound Wiretap Channels

    Directory of Open Access Journals (Sweden)

    Kramer Gerhard

    2009-01-01

    Full Text Available Abstract This paper considers the compound wiretap channel, which generalizes Wyner's wiretap model to allow the channels to the (legitimate receiver and to the eavesdropper to take a number of possible states. No matter which states occur, the transmitter guarantees that the receiver decodes its message and that the eavesdropper is kept in full ignorance about the message. The compound wiretap channel can also be viewed as a multicast channel with multiple eavesdroppers, in which the transmitter sends information to all receivers and keeps the information secret from all eavesdroppers. For the discrete memoryless channel, lower and upper bounds on the secrecy capacity are derived. The secrecy capacity is established for the degraded channel and the semideterministic channel with one receiver. The parallel Gaussian channel is further studied. The secrecy capacity and the secrecy degree of freedom ( are derived for the degraded case with one receiver. Schemes to achieve the for the case with two receivers and two eavesdroppers are constructed to demonstrate the necessity of a prefix channel in encoder design. Finally, the multi-antenna (i.e., MIMO compound wiretap channel is studied. The secrecy capacity is established for the degraded case and an achievable is given for the general case.

  18. ATP Release Channels

    Directory of Open Access Journals (Sweden)

    Akiyuki Taruno

    2018-03-01

    Full Text Available Adenosine triphosphate (ATP has been well established as an important extracellular ligand of autocrine signaling, intercellular communication, and neurotransmission with numerous physiological and pathophysiological roles. In addition to the classical exocytosis, non-vesicular mechanisms of cellular ATP release have been demonstrated in many cell types. Although large and negatively charged ATP molecules cannot diffuse across the lipid bilayer of the plasma membrane, conductive ATP release from the cytosol into the extracellular space is possible through ATP-permeable channels. Such channels must possess two minimum qualifications for ATP permeation: anion permeability and a large ion-conducting pore. Currently, five groups of channels are acknowledged as ATP-release channels: connexin hemichannels, pannexin 1, calcium homeostasis modulator 1 (CALHM1, volume-regulated anion channels (VRACs, also known as volume-sensitive outwardly rectifying (VSOR anion channels, and maxi-anion channels (MACs. Recently, major breakthroughs have been made in the field by molecular identification of CALHM1 as the action potential-dependent ATP-release channel in taste bud cells, LRRC8s as components of VRACs, and SLCO2A1 as a core subunit of MACs. Here, the function and physiological roles of these five groups of ATP-release channels are summarized, along with a discussion on the future implications of understanding these channels.

  19. Weighted Least Squares Techniques for Improved Received Signal Strength Based Localization

    Directory of Open Access Journals (Sweden)

    José R. Casar

    2011-09-01

    Full Text Available The practical deployment of wireless positioning systems requires minimizing the calibration procedures while improving the location estimation accuracy. Received Signal Strength localization techniques using propagation channel models are the simplest alternative, but they are usually designed under the assumption that the radio propagation model is to be perfectly characterized a priori. In practice, this assumption does not hold and the localization results are affected by the inaccuracies of the theoretical, roughly calibrated or just imperfect channel models used to compute location. In this paper, we propose the use of weighted multilateration techniques to gain robustness with respect to these inaccuracies, reducing the dependency of having an optimal channel model. In particular, we propose two weighted least squares techniques based on the standard hyperbolic and circular positioning algorithms that specifically consider the accuracies of the different measurements to obtain a better estimation of the position. These techniques are compared to the standard hyperbolic and circular positioning techniques through both numerical simulations and an exhaustive set of real experiments on different types of wireless networks (a wireless sensor network, a WiFi network and a Bluetooth network. The algorithms not only produce better localization results with a very limited overhead in terms of computational cost but also achieve a greater robustness to inaccuracies in channel modeling.

  20. Channel Estimation and Optimal Power Allocation for a Multiple-Antenna OFDM System

    Directory of Open Access Journals (Sweden)

    Yao Kung

    2002-01-01

    Full Text Available We propose combining channel estimation and optimal power allocation approaches for a multiple-antenna orthogonal frequency division multiplexing (OFDM system in high-speed transmission applications. We develop a least-square channel estimation approach, derive the performance bound of the estimator, and investigate the optimal training sequences for initial channel acquisition. Based on the channel estimates, the optimal power allocation solution which maximizes the bandwidth efficiency is derived under power and quality of service (Qos (symbol error rate constraints. It is shown that combining channel tracking and adaptive power allocation can dramatically enhance the outage capacity of an OFDM multiple-antenna system when severing fading occurs.

  1. Volume Regulated Channels

    DEFF Research Database (Denmark)

    Klausen, Thomas Kjær

    of volume perturbations evolution have developed system of channels and transporters to tightly control volume homeostasis. In the past decades evidence has been mounting, that the importance of these volume regulated channels and transporters are not restricted to the defense of cellular volume...... but are also essential for a number of physiological processes such as proliferation, controlled cell death, migration and endocrinology. The thesis have been focusing on two Channels, namely the swelling activated Cl- channel (ICl, swell) and the transient receptor potential Vanilloid (TRPV4) channel. I: Cl......- serves a multitude of functions in the mammalian cell, regulating the membrane potential (Em), cell volume, protein activity and the driving force for facilitated transporters giving Cl- and Cl- channels a major potential of regulating cellular function. These functions include control of the cell cycle...

  2. New approach to breast cancer CAD using partial least squares and kernel-partial least squares

    Science.gov (United States)

    Land, Walker H., Jr.; Heine, John; Embrechts, Mark; Smith, Tom; Choma, Robert; Wong, Lut

    2005-04-01

    Breast cancer is second only to lung cancer as a tumor-related cause of death in women. Currently, the method of choice for the early detection of breast cancer is mammography. While sensitive to the detection of breast cancer, its positive predictive value (PPV) is low, resulting in biopsies that are only 15-34% likely to reveal malignancy. This paper explores the use of two novel approaches called Partial Least Squares (PLS) and Kernel-PLS (K-PLS) to the diagnosis of breast cancer. The approach is based on optimization for the partial least squares (PLS) algorithm for linear regression and the K-PLS algorithm for non-linear regression. Preliminary results show that both the PLS and K-PLS paradigms achieved comparable results with three separate support vector learning machines (SVLMs), where these SVLMs were known to have been trained to a global minimum. That is, the average performance of the three separate SVLMs were Az = 0.9167927, with an average partial Az (Az90) = 0.5684283. These results compare favorably with the K-PLS paradigm, which obtained an Az = 0.907 and partial Az = 0.6123. The PLS paradigm provided comparable results. Secondly, both the K-PLS and PLS paradigms out performed the ANN in that the Az index improved by about 14% (Az ~ 0.907 compared to the ANN Az of ~ 0.8). The "Press R squared" value for the PLS and K-PLS machine learning algorithms were 0.89 and 0.9, respectively, which is in good agreement with the other MOP values.

  3. Bandwidth efficient channel estimation method for airborne hyperspectral data transmission in sparse doubly selective communication channels

    Science.gov (United States)

    Vahidi, Vahid; Saberinia, Ebrahim; Regentova, Emma E.

    2017-10-01

    A channel estimation (CE) method based on compressed sensing (CS) is proposed to estimate the sparse and doubly selective (DS) channel for hyperspectral image transmission from unmanned aircraft vehicles to ground stations. The proposed method contains three steps: (1) the priori estimate of the channel by orthogonal matching pursuit (OMP), (2) calculation of the linear minimum mean square error (LMMSE) estimate of the received pilots given the estimated channel, and (3) estimate of the complex amplitudes and Doppler shifts of the channel using the enhanced received pilot data applying a second round of a CS algorithm. The proposed method is named DS-LMMSE-OMP, and its performance is evaluated by simulating transmission of AVIRIS hyperspectral data via the communication channel and assessing their fidelity for the automated analysis after demodulation. The performance of the DS-LMMSE-OMP approach is compared with that of two other state-of-the-art CE methods. The simulation results exhibit up to 8-dB figure of merit in the bit error rate and 50% improvement in the hyperspectral image classification accuracy.

  4. HIPPI and Fibre Channel

    International Nuclear Information System (INIS)

    Tolmie, D.E.

    1992-01-01

    The High-Performance Parallel Interface (HIPPI) and Fibre Channel are near-gigabit per second data communications interfaces being developed in ANSI standards Task Group X3T9.3. HIPPI is the current interface of choice in the high-end and supercomputer arena, and Fibre Channel is a follow-on effort. HIPPI came from a local area network background, and Fibre Channel came from a mainframe to peripheral interface background

  5. Nuclear reactor coolant channels

    International Nuclear Information System (INIS)

    Macbeth, R.V.

    1978-01-01

    Reference is made to coolant channels for pressurised water and boiling water reactors and the arrangement described aims to improve heat transfer between the fuel rods and the coolant. Baffle means extending axially within the channel are provided and disposed relative to the fuel rods so as to restrict flow oscillations occurring within the coolant from being propagated transversely to the axis of the channel. (UK)

  6. New Channels, New Possibilities

    DEFF Research Database (Denmark)

    Pieterson, Willem; Ebbers, Wolfgang; Østergaard Madsen, Christian

    2017-01-01

    In this contribution we discuss the characteristics of what we call the fourth generation of public sector service channels: social robots. Based on a review of relevant literature we discuss their characteristics and place into multi-channel models of service delivery. We argue that social robots......-channel models of service delivery. This is especially relevant given the current lack of evaluations of such models, the broad range of channels available, and their different stages of deployment at governments around the world. Nevertheless, social robots offer an potentially very relevant addition...

  7. Calcium Channel Blockers

    Science.gov (United States)

    ... Certain calcium channel blockers interact with grapefruit products. Kaplan NM, et al. Treatment of hypertension: Drug therapy. In: Kaplan's Clinical Hypertension. 11th ed. Philadelphia, Pa.: Wolters Kluwer ...

  8. A channel profile analyser

    International Nuclear Information System (INIS)

    Gobbur, S.G.

    1983-01-01

    It is well understood that due to the wide band noise present in a nuclear analog-to-digital converter, events at the boundaries of adjacent channels are shared. It is a difficult and laborious process to exactly find out the shape of the channels at the boundaries. A simple scheme has been developed for the direct display of channel shape of any type of ADC on a cathode ray oscilliscope display. This has been accomplished by sequentially incrementing the reference voltage of a precision pulse generator by a fraction of a channel and storing ADC data in alternative memory locations of a multichannel pulse height analyser. Alternative channels are needed due to the sharing at the boundaries of channels. In the flat region of the profile alternate memory locations are channels with zero counts and channels with the full scale counts. At the boundaries all memory locations will have counts. The shape of this is a direct display of the channel boundaries. (orig.)

  9. Low-Complexity Bayesian Estimation of Cluster-Sparse Channels

    KAUST Repository

    Ballal, Tarig; Al-Naffouri, Tareq Y.; Ahmed, Syed

    2015-01-01

    This paper addresses the problem of channel impulse response estimation for cluster-sparse channels under the Bayesian estimation framework. We develop a novel low-complexity minimum mean squared error (MMSE) estimator by exploiting the sparsity of the received signal profile and the structure of the measurement matrix. It is shown that due to the banded Toeplitz/circulant structure of the measurement matrix, a channel impulse response, such as underwater acoustic channel impulse responses, can be partitioned into a number of orthogonal or approximately orthogonal clusters. The orthogonal clusters, the sparsity of the channel impulse response and the structure of the measurement matrix, all combined, result in a computationally superior realization of the MMSE channel estimator. The MMSE estimator calculations boil down to simpler in-cluster calculations that can be reused in different clusters. The reduction in computational complexity allows for a more accurate implementation of the MMSE estimator. The proposed approach is tested using synthetic Gaussian channels, as well as simulated underwater acoustic channels. Symbol-error-rate performance and computation time confirm the superiority of the proposed method compared to selected benchmark methods in systems with preamble-based training signals transmitted over clustersparse channels.

  10. Low-Complexity Bayesian Estimation of Cluster-Sparse Channels

    KAUST Repository

    Ballal, Tarig

    2015-09-18

    This paper addresses the problem of channel impulse response estimation for cluster-sparse channels under the Bayesian estimation framework. We develop a novel low-complexity minimum mean squared error (MMSE) estimator by exploiting the sparsity of the received signal profile and the structure of the measurement matrix. It is shown that due to the banded Toeplitz/circulant structure of the measurement matrix, a channel impulse response, such as underwater acoustic channel impulse responses, can be partitioned into a number of orthogonal or approximately orthogonal clusters. The orthogonal clusters, the sparsity of the channel impulse response and the structure of the measurement matrix, all combined, result in a computationally superior realization of the MMSE channel estimator. The MMSE estimator calculations boil down to simpler in-cluster calculations that can be reused in different clusters. The reduction in computational complexity allows for a more accurate implementation of the MMSE estimator. The proposed approach is tested using synthetic Gaussian channels, as well as simulated underwater acoustic channels. Symbol-error-rate performance and computation time confirm the superiority of the proposed method compared to selected benchmark methods in systems with preamble-based training signals transmitted over clustersparse channels.

  11. Space and protest: A tale of two Egyptian squares

    OpenAIRE

    Mohamed, A.A.; Van Nes, A.; Salheen, M.A.

    2015-01-01

    Protests and revolts take place in public space. How they can be controlled or how protests develop depend on the physical layout of the built environment. This study reveals the relationship between urban space and protest for two Egyptian squares: Tahrir Square and Rabaa Al-Adawiya in Cairo. For analysis, the research uses space syntax method. The results of this analysis are then compared with descriptions of the protest behaviour. As it turns out, the spatial properties of Tahrir square s...

  12. Microstructural evolution of bainitic steel severely deformed by equal channel angular pressing.

    Science.gov (United States)

    Nili-Ahmadabadi, M; Haji Akbari, F; Rad, F; Karimi, Z; Iranpour, M; Poorganji, B; Furuhara, T

    2010-09-01

    High Si bainitic steel has been received much of interest because of combined ultra high strength, good ductility along with high wear resistance. In this study a high Si bainitic steel (Fe-0.22C-2.0Si-3.0Mn) was used with a proper microstructure which could endure severe plastic deformation. In order to study the effect of severe plastic deformation on the microstructure and properties of bainitic steel, Equal Channel Angular Pressing was performed in two passes at room temperature. Optical, SEM and TEM microscopies were used to examine the microstructure of specimens before and after Equal Channel Angular Pressing processing. X-ray diffraction was used to measure retained austenite after austempering and Equal Channel Angular Pressing processing. It can be seen that retained austenite picks had removed after Equal Channel Angular Pressing which could attributed to the transformation of austenite to martensite during severe plastic deformation. Enhancement of hardness values by number of Equal Channel Angular Pressing confirms this idea.

  13. A linearization of quantum channels

    Science.gov (United States)

    Crowder, Tanner

    2015-06-01

    Because the quantum channels form a compact, convex set, we can express any quantum channel as a convex combination of extremal channels. We give a Euclidean representation for the channels whose inverses are also valid channels; these are a subset of the extreme points. They form a compact, connected Lie group, and we calculate its Lie algebra. Lastly, we calculate a maximal torus for the group and provide a constructive approach to decomposing any invertible channel into a product of elementary channels.

  14. Omni channel fashion shopping

    NARCIS (Netherlands)

    Kemperman, A.D.A.M.; van Delft, L.; Borgers, A.W.J.; Pantano, E.

    2015-01-01

    This chapter gives insight into consumers' online and offline fashion shopping behavior, consumers' omni-channel usage during the shopping process, and consumer fashion shopper segments. Based on a literature review, omni-channel shopping behavior during the shopping process was operationalized.

  15. Positive solution of non-square fully Fuzzy linear system of equation in general form using least square method

    Directory of Open Access Journals (Sweden)

    Reza Ezzati

    2014-08-01

    Full Text Available In this paper, we propose the least square method for computing the positive solution of a non-square fully fuzzy linear system. To this end, we use Kaffman' arithmetic operations on fuzzy numbers \\cite{17}. Here, considered existence of exact solution using pseudoinverse, if they are not satisfy in positive solution condition, we will compute fuzzy vector core and then we will obtain right and left spreads of positive fuzzy vector by introducing constrained least squares problem. Using our proposed method, non-square fully fuzzy linear system of equations always has a solution. Finally, we illustrate the efficiency of proposed method by solving some numerical examples.

  16. Channel electron multipliers

    International Nuclear Information System (INIS)

    Seidman, A.; Avrahami, Z.; Sheinfux, B.; Grinberg, J.

    1976-01-01

    A channel electron multiplier is described having a tubular wall coated with a secondary-electron emitting material and including an electric field for accelerating the electrons, the electric field comprising a plurality of low-resistive conductive rings each alternating with a high-resistive insulating ring. The thickness of the low-resistive rings is many times larger than that of the high-resistive rings, being in the order of tens of microns for the low-resistive rings and at least one order of magnitude lower for the high-resistive rings; and the diameter of the channel tubular walls is also many times larger than the thickness of the high-resistive rings. Both single-channel and multiple-channel electron multipliers are described. A very important advantage, particularly in making multiple-channel multipliers, is the simplicity of the procedure that may be used in constructing such multipliers. Other operational advantages are described

  17. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter

    2014-01-01

    About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...... drive the late repolarization of the ventricle with some redundancy, and in atria this repolarization reserve is supplemented by the fairly atrial-specific KV1.5, Kir3, KCa, and K2P channels. The role of the latter two subtypes in atria is currently being clarified, and several findings indicate...... that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K(+) channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure...

  18. Cl- channels in apoptosis

    DEFF Research Database (Denmark)

    Wanitchakool, Podchanart; Ousingsawat, Jiraporn; Sirianant, Lalida

    2016-01-01

    A remarkable feature of apoptosis is the initial massive cell shrinkage, which requires opening of ion channels to allow release of K(+), Cl(-), and organic osmolytes to drive osmotic water movement and cell shrinkage. This article focuses on the role of the Cl(-) channels LRRC8, TMEM16/anoctamin......, and cystic fibrosis transmembrane conductance regulator (CFTR) in cellular apoptosis. LRRC8A-E has been identified as a volume-regulated anion channel expressed in many cell types. It was shown to be required for regulatory and apoptotic volume decrease (RVD, AVD) in cultured cell lines. Its presence also......(-) channels or as regulators of other apoptotic Cl(-) channels, such as LRRC8. CFTR has been known for its proapoptotic effects for some time, and this effect may be based on glutathione release from the cell and increase in cytosolic reactive oxygen species (ROS). Although we find that CFTR is activated...

  19. CHANNEL ESTIMATION TECHNIQUE

    DEFF Research Database (Denmark)

    2015-01-01

    A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over the communicat......A method includes determining a sequence of first coefficient estimates of a communication channel based on a sequence of pilots arranged according to a known pilot pattern and based on a receive signal, wherein the receive signal is based on the sequence of pilots transmitted over...... the communication channel. The method further includes determining a sequence of second coefficient estimates of the communication channel based on a decomposition of the first coefficient estimates in a dictionary matrix and a sparse vector of the second coefficient estimates, the dictionary matrix including...... filter characteristics of at least one known transceiver filter arranged in the communication channel....

  20. Workability Limits of Magnesium Alloy AZ31B Subjected to Equal Channel Angular Pressing

    Science.gov (United States)

    Arun, M. S.; Chakkingal, Uday

    2018-03-01

    Equal channel angular pressing (ECAP) is an important severe plastic deformation process to produce ultrafine grained microstructures in metals and alloys. Magnesium and its alloys generally possess poor workability at temperatures below 250 °C. This investigation examines the influence of different passes and processing routes of ECAP on improving the workability of Mg alloy AZ31B. ECAP was carried out for three passes using a die of angle 120° using processing routes Bc and C. The operating temperature was 523 K for the first pass and 423 K for the subsequent two passes. The resultant microstructure and mechanical properties were determined. Workability of the alloy at 423 K (150 °C) was determined using upsetting experiments on cylindrical specimens machined from the annealed and ECAPed samples. Workability limit diagrams have been constructed for the various processed conditions. The workability data generated were also analyzed using five different workability criteria (also referred to as ductile fracture models) and the material constants for these five models were evaluated. Specimens processed by two passes through route C (pass 2C) exhibits better workability compared to other passes since the workability limit line after this pass shows maximum safe working area and lies above the other workability lines. Among the five different workability criteria investigated, the Freudenthal workability criterion is more suitable for prediction of failure in this alloy.

  1. The nonabelian tensor square of a bieberbach group with ...

    African Journals Online (AJOL)

    The main objective of this paper is to compute the nonabelian tensor square of one Bieberbach group with elementary abelian 2-group point group of dimension three by using the computational method of the nonabelian tensor square for polycyclic groups. The finding of the computation showed that the nonabelian tensor ...

  2. Your Chi-Square Test Is Statistically Significant: Now What?

    Science.gov (United States)

    Sharpe, Donald

    2015-01-01

    Applied researchers have employed chi-square tests for more than one hundred years. This paper addresses the question of how one should follow a statistically significant chi-square test result in order to determine the source of that result. Four approaches were evaluated: calculating residuals, comparing cells, ransacking, and partitioning. Data…

  3. Space and protest : A tale of two Egyptian squares

    NARCIS (Netherlands)

    Mohamed, A.A.; Van Nes, A.; Salheen, M.A.

    2015-01-01

    Protests and revolts take place in public space. How they can be controlled or how protests develop depend on the physical layout of the built environment. This study reveals the relationship between urban space and protest for two Egyptian squares: Tahrir Square and Rabaa Al-Adawiya in Cairo. For

  4. Least-squares reverse time migration of multiples

    KAUST Repository

    Zhang, Dongliang; Schuster, Gerard T.

    2013-01-01

    The theory of least-squares reverse time migration of multiples (RTMM) is presented. In this method, least squares migration (LSM) is used to image free-surface multiples where the recorded traces are used as the time histories of the virtual

  5. TINGKAT KEPUASAN PELANGGAN TERHADAP PELAYANAN DI KFC MAKASSAR TOWN SQUARE

    OpenAIRE

    RAMADHANI, IRMA

    2017-01-01

    2017 Penelitian ini bertujuan untuk mengetahui tingkat kepuasan pelanggan terhadap pelayanan di KFC Makassar Town Square. Penelitian ini dilaksanakan terhadap pelanggan KFC Makassar Town Square yang telah bertransaksi lebih dari satu kali. Penelitian ini merupakan penelitian kuantitatif deskriptif dengan mendeskripsikan atau menggambarkan tentang tingkat kepuasan pelanggan terhadap pelayanan. Jumlah sampel penelitian 83 pelanggan KFC Makassar Town. Analisis data menggunak...

  6. Solution of a Complex Least Squares Problem with Constrained Phase.

    Science.gov (United States)

    Bydder, Mark

    2010-12-30

    The least squares solution of a complex linear equation is in general a complex vector with independent real and imaginary parts. In certain applications in magnetic resonance imaging, a solution is desired such that each element has the same phase. A direct method for obtaining the least squares solution to the phase constrained problem is described.

  7. note: The least square nucleolus is a general nucleolus

    OpenAIRE

    Elisenda Molina; Juan Tejada

    2000-01-01

    This short note proves that the least square nucleolus (Ruiz et al. (1996)) and the lexicographical solution (Sakawa and Nishizaki (1994)) select the same imputation in each game with nonempty imputation set. As a consequence the least square nucleolus is a general nucleolus (Maschler et al. (1992)).

  8. On root mean square approximation by exponential functions

    OpenAIRE

    Sharipov, Ruslan

    2014-01-01

    The problem of root mean square approximation of a square integrable function by finite linear combinations of exponential functions is considered. It is subdivided into linear and nonlinear parts. The linear approximation problem is solved. Then the nonlinear problem is studied in some particular example.

  9. Application of least-squares method to decay heat evaluation

    International Nuclear Information System (INIS)

    Schmittroth, F.; Schenter, R.E.

    1976-01-01

    Generalized least-squares methods are applied to decay-heat experiments and summation calculations to arrive at evaluated values and uncertainties for the fission-product decay-heat from the thermal fission of 235 U. Emphasis is placed on a proper treatment of both statistical and correlated uncertainties in the least-squares method

  10. Quantitative flow characteristics for side-by-side square cylinders via PIV

    Directory of Open Access Journals (Sweden)

    Dogan Sercan

    2012-04-01

    Full Text Available In this study, instantaneous and time-averaged flow structures downstream of the sharp-edged single and two and three side-by-side square cylinders (SCs immersed in a uniform open channel water flow were studied by a technique of particle image velocimetry (PIV. Experimental results of wake flow structures were presented for gap ratios (G/D in the range of 1.0”G/D”3.0 for Reynolds number values of 1050, 2450 and 3400. Flow structures depending on the square cylinder (SC configurations and Reynolds number were discussed. It has been found that the development of the vortex shedding as well as the flow structure were substantially altered for side-by-side SCs comparing to the single SC. Asymmetrical and biased wake structures were observed because of the jetlike flow between the SCs for two SCs cases for the gap ratio less than 2.0. Depending on the gap spacing between the SCs, the interaction results of time2 averaged vorticity, velocity vector field, Reynolds stress correlations and streamline patterns in the wake region form a distinguished flow structure. Strouhal numbers for the single square cylinder for 1050≤Re≤3400 are found in the range of 0.12-0.13. The present results have supported the previous works by providing detailed quantitative experimental information with PIV in the wake region of the SC and might be helpful for validation of numerical studies and designers.

  11. Comparing implementations of penalized weighted least-squares sinogram restoration

    International Nuclear Information System (INIS)

    Forthmann, Peter; Koehler, Thomas; Defrise, Michel; La Riviere, Patrick

    2010-01-01

    Purpose: A CT scanner measures the energy that is deposited in each channel of a detector array by x rays that have been partially absorbed on their way through the object. The measurement process is complex and quantitative measurements are always and inevitably associated with errors, so CT data must be preprocessed prior to reconstruction. In recent years, the authors have formulated CT sinogram preprocessing as a statistical restoration problem in which the goal is to obtain the best estimate of the line integrals needed for reconstruction from the set of noisy, degraded measurements. The authors have explored both penalized Poisson likelihood (PL) and penalized weighted least-squares (PWLS) objective functions. At low doses, the authors found that the PL approach outperforms PWLS in terms of resolution-noise tradeoffs, but at standard doses they perform similarly. The PWLS objective function, being quadratic, is more amenable to computational acceleration than the PL objective. In this work, the authors develop and compare two different methods for implementing PWLS sinogram restoration with the hope of improving computational performance relative to PL in the standard-dose regime. Sinogram restoration is still significant in the standard-dose regime since it can still outperform standard approaches and it allows for correction of effects that are not usually modeled in standard CT preprocessing. Methods: The authors have explored and compared two implementation strategies for PWLS sinogram restoration: (1) A direct matrix-inversion strategy based on the closed-form solution to the PWLS optimization problem and (2) an iterative approach based on the conjugate-gradient algorithm. Obtaining optimal performance from each strategy required modifying the naive off-the-shelf implementations of the algorithms to exploit the particular symmetry and sparseness of the sinogram-restoration problem. For the closed-form approach, the authors subdivided the large matrix

  12. Coupling parameter series expansion for fluid with square-well plus repulsive-square-barrier potential

    Directory of Open Access Journals (Sweden)

    Shiqi Zhou

    2013-10-01

    Full Text Available Monte Carlo simulations in the canonical ensemble are performed for fluid with potential consisting of a square-well plus a square-barrier to obtain thermodynamic properties such as pressure, excess energy, constant volume excess heat capacity, and excess chemical potential, and structural property such as radial distribution function. The simulations cover a wide density range for the fluid phase, several temperatures, and different combinations of the parameters defining the potential. These simulation data have been used to test performances of a coupling parameter series expansion (CPSE recently proposed by one of the authors [S. Zhou, Phys. Rev. E 74, 031119 (2006], and a traditional 2nd-order high temperature series expansion (HTSE based on a macroscopic compressibility approximation (MAC used with confidence since its introduction in 1967. It is found that (i the MCA-based 2nd-order HTSE unexpectedly and depressingly fails for most situations investigated, and the present simulation results can serve well as strict criteria for testing liquid state theories. (ii The CPSE perturbation scheme is shown to be capable of predicting very accurately most of the thermodynamic properties simulated, but the most appropriate level of truncating the CPSE differs and depends on the range of the potential to be calculated; in particular, the shorter the potential range is, the higher the most appropriate truncating level can be, and along with rising of the potential range the performance of the CPSE perturbation scheme will decrease at higher truncating level. (iii The CPSE perturbation scheme can calculate satisfactorily bulk fluid rdf, and such calculations can be done for all fluid states of the whole phase diagram. (iv The CPSE is a convergent series at higher temperatures, but show attribute of asymptotic series at lower temperatures, and as a result, the surest asymptotic value occurs at lower-order truncation.

  13. Enumeration of self-avoiding walks on the square lattice

    International Nuclear Information System (INIS)

    Jensen, Iwan

    2004-01-01

    We describe a new algorithm for the enumeration of self-avoiding walks on the square lattice. Using up to 128 processors on a HP Alpha server cluster we have enumerated the number of self-avoiding walks on the square lattice to length 71. Series for the metric properties of mean-square end-to-end distance, mean-square radius of gyration and mean-square distance of monomers from the end points have been derived to length 59. An analysis of the resulting series yields accurate estimates of the critical exponents γ and ν confirming predictions of their exact values. Likewise we obtain accurate amplitude estimates yielding precise values for certain universal amplitude combinations. Finally we report on an analysis giving compelling evidence that the leading non-analytic correction-to-scaling exponent Δ 1 = 3/2

  14. Coherifying quantum channels

    Science.gov (United States)

    Korzekwa, Kamil; Czachórski, Stanisław; Puchała, Zbigniew; Życzkowski, Karol

    2018-04-01

    Is it always possible to explain random stochastic transitions between states of a finite-dimensional system as arising from the deterministic quantum evolution of the system? If not, then what is the minimal amount of randomness required by quantum theory to explain a given stochastic process? Here, we address this problem by studying possible coherifications of a quantum channel Φ, i.e., we look for channels {{{Φ }}}{ \\mathcal C } that induce the same classical transitions T, but are ‘more coherent’. To quantify the coherence of a channel Φ we measure the coherence of the corresponding Jamiołkowski state J Φ. We show that the classical transition matrix T can be coherified to reversible unitary dynamics if and only if T is unistochastic. Otherwise the Jamiołkowski state {J}{{Φ }}{ \\mathcal C } of the optimally coherified channel is mixed, and the dynamics must necessarily be irreversible. To assess the extent to which an optimal process {{{Φ }}}{ \\mathcal C } is indeterministic we find explicit bounds on the entropy and purity of {J}{{Φ }}{ \\mathcal C }, and relate the latter to the unitarity of {{{Φ }}}{ \\mathcal C }. We also find optimal coherifications for several classes of channels, including all one-qubit channels. Finally, we provide a non-optimal coherification procedure that works for an arbitrary channel Φ and reduces its rank (the minimal number of required Kraus operators) from {d}2 to d.

  15. CANDU channel flow verification

    International Nuclear Information System (INIS)

    Mazalu, N.; Negut, Gh.

    1997-01-01

    The purpose of this evaluation was to obtain accurate information on each channel flow that enables us to assess precisely the level of reactor thermal power and, for reasons of safety, to establish which channel is boiling. In order to assess the channel flow parameters, computer simulations were done with the NUCIRC code and the results were checked by measurements. The complete channel flow measurements were made in the zero power cold condition. In hot conditions there were made flow measurements using the Shut Down System 1 (SDS 1) flow devices from 0.1 % F.P. up to 100 % F.P. The NUCIRC prediction for CANDU channel flows and the measurements by Ultrasonic Flow Meter at zero power cold conditions and SDS 1 flow channel measurements at different reactor power levels showed an acceptable agreement. The 100 % F.P. average errors for channel flow of R, shows that suitable NUCIRC flow assessment can be made. So, it can be done a fair prediction of the reactor power distribution. NUCIRC can predict accurately the onset of boiling and helps to warn at the possible power instabilities at high powers or it can detect the flow blockages. The thermal hydraulic analyst has in NUCIRC a suitable tool to do accurate predictions for the thermal hydraulic parameters for different steady state power levels which subsequently leads to an optimal CANDU reactor operation. (authors)

  16. Reconfigurable virtual electrowetting channels.

    Science.gov (United States)

    Banerjee, Ananda; Kreit, Eric; Liu, Yuguang; Heikenfeld, Jason; Papautsky, Ian

    2012-02-21

    Lab-on-a-chip systems rely on several microfluidic paradigms. The first uses a fixed layout of continuous microfluidic channels. Such lab-on-a-chip systems are almost always application specific and far from a true "laboratory." The second involves electrowetting droplet movement (digital microfluidics), and allows two-dimensional computer control of fluidic transport and mixing. The merging of the two paradigms in the form of programmable electrowetting channels takes advantage of both the "continuous" functionality of rigid channels based on which a large number of applications have been developed to date and the "programmable" functionality of digital microfluidics that permits electrical control of on-chip functions. In this work, we demonstrate for the first time programmable formation of virtual microfluidic channels and their continuous operation with pressure driven flows using an electrowetting platform. Experimental, theoretical, and numerical analyses of virtual channel formation with biologically relevant electrolyte solutions and electrically-programmable reconfiguration are presented. We demonstrate that the "wall-less" virtual channels can be formed reliably and rapidly, with propagation rates of 3.5-3.8 mm s(-1). Pressure driven transport in these virtual channels at flow rates up to 100 μL min(-1) is achievable without distortion of the channel shape. We further demonstrate that these virtual channels can be switched on-demand between multiple inputs and outputs. Ultimately, we envision a platform that would provide rapid prototyping of microfluidic concepts and would be capable of a vast library of functions and benefitting applications from clinical diagnostics in resource-limited environments to rapid system prototyping to high throughput pharmaceutical applications.

  17. On Channel Estimation for OFDM/TDM Using MMSE-FDE in a Fast Fading Channel

    Directory of Open Access Journals (Sweden)

    Gacanin Haris

    2009-01-01

    Full Text Available Abstract MMSE-FDE can improve the transmission performance of OFDM combined with time division multiplexing (OFDM/TDM, but knowledge of the channel state information and the noise variance is required to compute the MMSE weight. In this paper, a performance evaluation of OFDM/TDM using MMSE-FDE with pilot-assisted channel estimation over a fast fading channel is presented. To improve the tracking ability against fast fading a robust pilot-assisted channel estimation is presented that uses time-domain filtering on a slot-by-slot basis and frequency-domain interpolation. We derive the mean square error (MSE of the channel estimator and then discuss a tradeoff between improving the tracking ability against fading and the noise reduction. The achievable bit error rate (BER performance is evaluated by computer simulation and compared with conventional OFDM. It is shown that the OFDM/TDM using MMSE-FDE achieves a lower BER and a better tracking ability against fast fading in comparison with conventional OFDM.

  18. Evaluation channel performance in multichannel environments

    NARCIS (Netherlands)

    Gensler, S.; Dekimpe, M.; Skiera, B.

    2007-01-01

    Evaluating channel performance is crucial for actively managing multiple sales channels, and requires understanding the customers' channel preferences. Two key components of channel performance are (i) the existing customers' intrinsic loyalty to a particular channel and (ii) the channel's ability

  19. Channel follower leakage restrictor

    International Nuclear Information System (INIS)

    Williamson, H.E.; Smith, B.A.

    1977-01-01

    An improved means is provided to control coolant leakage between the flow channel and the lower tie plate of a nuclear fuel assembly. The means includes an opening in the lower tie plate and a movable element adjacent thereto. The coolant pressure within the tie plate biases the movable means toward the inner surface of the surrounding flow channel to compensate for any movement of the flow channel away from the lower tie plate to thereby control the leakage of coolant flow from the fuel assemblies to the spaces among the fuel assemblies of the core. 9 figures

  20. Direct channel problems and phenomena

    International Nuclear Information System (INIS)

    Cutkosky, R.E.

    1975-01-01

    Direct channel problems and phenomena are considered covering the need for precision hadron spectroscopy, the data base for precision hadron spectroscopy, some relations between direct-channel and cross-channel effects, and spin rotation phenomena

  1. The Channel Estimation and Modeling in High Altitude Platform Station Wireless Communication Dynamic Network

    Directory of Open Access Journals (Sweden)

    Xiaoyang Liu

    2017-01-01

    Full Text Available In order to analyze the channel estimation performance of near space high altitude platform station (HAPS in wireless communication system, the structure and formation of HAPS are studied in this paper. The traditional Least Squares (LS channel estimation method and Singular Value Decomposition-Linear Minimum Mean-Squared (SVD-LMMS channel estimation method are compared and investigated. A novel channel estimation method and model are proposed. The channel estimation performance of HAPS is studied deeply. The simulation and theoretical analysis results show that the performance of the proposed method is better than the traditional methods. The lower Bit Error Rate (BER and higher Signal Noise Ratio (SNR can be obtained by the proposed method compared with the LS and SVD-LMMS methods.

  2. Computational Investigations in Rectangular Convergent and Divergent Ribbed Channels

    Science.gov (United States)

    Sivakumar, Karthikeyan; Kulasekharan, N.; Natarajan, E.

    2018-05-01

    Computational investigations on the rib turbulated flow inside a convergent and divergent rectangular channel with square ribs of different rib heights and different Reynolds numbers (Re=20,000, 40,000 and 60,000). The ribs were arranged in a staggered fashion between the upper and lower surfaces of the test section. Computational investigations are carried out using computational fluid dynamic software ANSYS Fluent 14.0. Suitable solver settings like turbulence models were identified from the literature and the boundary conditions for the simulations on a solution of independent grid. Computations were carried out for both convergent and divergent channels with 0 (smooth duct), 1.5, 3, 6, 9 and 12 mm rib heights, to identify the ribbed channel with optimal performance, assessed using a thermo hydraulic performance parameter. The convergent and divergent rectangular channels show higher Nu values than the standard correlation values.

  3. Frequency Dependence of Measured Massive MIMO Channel Properties

    DEFF Research Database (Denmark)

    Oliveras Martínez, Àlex; Carvalho, Elisabeth De; Nielsen, Jesper Ødum

    2016-01-01

    A multi-user massive MIMO measurement campaign is conducted to study the channel propagation characteristics (e.g. user correlation, sum of eigenvalues and condition number), focusing on the stability over frequencies and the impact of the array aperture. We use 3 arrays with 64 antennas (6m linear...... array, 2m linear array and 25cm by 28cm squared 2D array) serving 8 users holding a handset with 2 antennas. The study of the measurements shows that the propagation characteristics of the channel are stable for all the measured frequencies. We also observe that user proximity and user handgrip...... stabilize the studied properties of the channel across the frequencies, and in such case the larger the aperture of the array the more stable the properties. The number of base station antennas improves the propagation characteristics of the channel and stabilizes the properties in the frequency domain....

  4. Spectrum unfolding by the least-squares methods

    International Nuclear Information System (INIS)

    Perey, F.G.

    1977-01-01

    The method of least squares is briefly reviewed, and the conditions under which it may be used are stated. From this analysis, a least-squares approach to the solution of the dosimetry neutron spectrum unfolding problem is introduced. The mathematical solution to this least-squares problem is derived from the general solution. The existence of this solution is analyzed in some detail. A chi 2 -test is derived for the consistency of the input data which does not require the solution to be obtained first. The fact that the problem is technically nonlinear, but should be treated in general as a linear one, is argued. Therefore, the solution should not be obtained by iteration. Two interpretations are made for the solution of the code STAY'SL, which solves this least-squares problem. The relationship of the solution to this least-squares problem to those obtained currently by other methods of solving the dosimetry neutron spectrum unfolding problem is extensively discussed. It is shown that the least-squares method does not require more input information than would be needed by current methods in order to estimate the uncertainties in their solutions. From this discussion it is concluded that the proposed least-squares method does provide the best complete solution, with uncertainties, to the problem as it is understood now. Finally, some implications of this method are mentioned regarding future work required in order to exploit its potential fully

  5. Many channel spectrum unfolding

    International Nuclear Information System (INIS)

    Najzer, M.; Glumac, B.; Pauko, M.

    1980-01-01

    The principle of the ITER unfolding code as used for the many channel spectrum unfolding is described. Its unfolding ability is tested on seven typical neutron spectra. The effect of the initial spectrum approximation upon the solution is discussed

  6. Channelized Streams in Iowa

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — This draft dataset consists of all ditches or channelized pieces of stream that could be identified using three input datasets; namely the1:24,000 National...

  7. Coding for optical channels

    CERN Document Server

    Djordjevic, Ivan; Vasic, Bane

    2010-01-01

    This unique book provides a coherent and comprehensive introduction to the fundamentals of optical communications, signal processing and coding for optical channels. It is the first to integrate the fundamentals of coding theory and optical communication.

  8. Sensing with Ion Channels

    CERN Document Server

    Martinac, Boris

    2008-01-01

    All living cells are able to detect and translate environmental stimuli into biologically meaningful signals. Sensations of touch, hearing, sight, taste, smell or pain are essential to the survival of all living organisms. The importance of sensory input for the existence of life thus justifies the effort made to understand its molecular origins. Sensing with Ion Channels focuses on ion channels as key molecules enabling biological systems to sense and process the physical and chemical stimuli that act upon cells in their living environment. Its aim is to serve as a reference to ion channel specialists and as a source of new information to non specialists who want to learn about the structural and functional diversity of ion channels and their role in sensory physiology.

  9. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  10. TRP channels: an overview

    DEFF Research Database (Denmark)

    Pedersen, Stine Falsig; Owsianik, Grzegorz; Nilius, Bernd

    2005-01-01

    The TRP ("transient receptor potential") family of ion channels now comprises more than 30 cation channels, most of which are permeable for Ca2+, and some also for Mg2+. On the basis of sequence homology, the TRP family can be divided in seven main subfamilies: the TRPC ('Canonical') family......, the TRPV ('Vanilloid') family, the TRPM ('Melastatin') family, the TRPP ('Polycystin') family, the TRPML ('Mucolipin') family, the TRPA ('Ankyrin') family, and the TRPN ('NOMPC') family. The cloning and characterization of members of this cation channel family has exploded during recent years, leading...... to a plethora of data on the roles of TRPs in a variety of tissues and species, including mammals, insects, and yeast. The present review summarizes the most pertinent recent evidence regarding the structural and functional properties of TRP channels, focusing on the regulation and physiology of mammalian TRPs....

  11. TAHRIR SQUARE: A Narrative of a Public Space

    Directory of Open Access Journals (Sweden)

    Hussam Hussein Salama

    2013-03-01

    Full Text Available This paper investigates the patterns of public discourse that occurred in Tahrir Square during the 18 days of the Egyptian Revolution. For protestors Tahrir Square became an urban utopia, a place of community engagement, collective projects, social discourse, and most importantly, freedom of speech and expression. This paper traces these forms of spatial adaptation, and the patterns of social organization and discourse that emerged in the square during that period. The paper builds on Henri Lefebvre’s interpretation of space and his three dimensional conceptualization: the perceived, the conceived, and the lived.

  12. The circumference of the square of a connected graph

    DEFF Research Database (Denmark)

    Brandt, S.; Muttel, J.; Rautenbach, D.

    2014-01-01

    The celebrated result of Fleischner states that the square of every 2-connected graph is Hamiltonian. We investigate what happens if the graph is just connected. For every n a parts per thousand yen 3, we determine the smallest length c(n) of a longest cycle in the square of a connected graph of ...... of order n and show that c(n) is a logarithmic function in n. Furthermore, for every c a parts per thousand yen 3, we characterize the connected graphs of largest order whose square contains no cycle of length at least c....

  13. Radix-16 Combined Division and Square Root Unit

    DEFF Research Database (Denmark)

    Nannarelli, Alberto

    2011-01-01

    Division and square root, based on the digitrecurrence algorithm, can be implemented in a combined unit. Several implementations of combined division/square root units have been presented mostly for radices 2 and 4. Here, we present a combined radix-16 unit obtained by overlapping two radix-4...... result digit selection functions, as it is normally done for division only units. The latency of the unit is reduced by retiming and low power methods are applied as well. The proposed unit is compared to a radix-4 combined division/square root unit, and to a radix-16 unit, obtained by cascading two...

  14. Authentication over Noisy Channels

    OpenAIRE

    Lai, Lifeng; Gamal, Hesham El; Poor, H. Vincent

    2008-01-01

    In this work, message authentication over noisy channels is studied. The model developed in this paper is the authentication theory counterpart of Wyner's wiretap channel model. Two types of opponent attacks, namely impersonation attacks and substitution attacks, are investigated for both single message and multiple message authentication scenarios. For each scenario, information theoretic lower and upper bounds on the opponent's success probability are derived. Remarkably, in both scenarios,...

  15. Channelling versus inversion

    DEFF Research Database (Denmark)

    Gale, A.S.; Surlyk, Finn; Anderskouv, Kresten

    2013-01-01

    Evidence from regional stratigraphical patterns in Santonian−Campanian chalk is used to infer the presence of a very broad channel system (5 km across) with a depth of at least 50 m, running NNW−SSE across the eastern Isle of Wight; only the western part of the channel wall and fill is exposed. W......−Campanian chalks in the eastern Isle of Wight, involving penecontemporaneous tectonic inversion of the underlying basement structure, are rejected....

  16. Stream Channel Stability.

    Science.gov (United States)

    1981-04-01

    Cycles of wetting and drying are also t ,v itiue swelling and shrinkage of the soil. S 11ied blocks or peds of soil fabric ,,ks. id downslope soil creep ...hydrographs of water and sediment at the point in question. By feeding the output from the hydrology-transport model into the finite element model...the banks as undercut banks fail. Channel irregularities such as seepage zones, cattle crossings, overbank drainage, buried channels, organic deposits

  17. Channeling and dynamic chaos

    Energy Technology Data Exchange (ETDEWEB)

    Bolotin, IU L; Gonchar, V IU; Truten, V I; Shulga, N F

    1986-01-01

    It is shown that axial channeling of relativistic electrons can give rise to the effect of dynamic chaos which involves essentially chaotic motion of a particle in the channel. The conditions leading to the effect of dynamic chaos and the manifestations of this effect in physical processes associated with the passage of particles through a crystal are examined using a silicon crystal as an example. 7 references.

  18. Course on Ionic Channels

    CERN Document Server

    1986-01-01

    This book is based on a series of lectures for a course on ionic channels held in Santiago, Chile, on November 17-20, 1984. It is intended as a tutorial guide on the properties, function, modulation, and reconstitution of ionic channels, and it should be accessible to graduate students taking their first steps in this field. In the presentation there has been a deliberate emphasis on the spe­ cific methodologies used toward the understanding of the workings and function of channels. Thus, in the first section, we learn to "read" single­ channel records: how to interpret them in the theoretical frame of kinetic models, which information can be extracted from gating currents in re­ lation to the closing and opening processes, and how ion transport through an open channel can be explained in terms of fluctuating energy barriers. The importance of assessing unequivocally the origin and purity of mem­ brane preparations and the use of membrane vesicles and optical tech­ niques in the stUGY of ionic channels a...

  19. Consumers Attitudes towards Internet and Brick and Mortar Store Channels Switching Behavior

    Directory of Open Access Journals (Sweden)

    Abdolrazagh MADAHI

    2014-12-01

    Full Text Available he purpose of this study is to examine the role of consumers’ behavioral attitude and intention toward channel switching behavior in regards to Internet and brick and mortar store channels in Malaysia. The survey instrument administered to the Malaysian consumers from regions of Klang Valley and Penang. A total of 497 completed surveys were obtained. Partial least squares (PLS based structural equation modeling (SEM technique was used to analyze data. A total of 497 completed surveys were obtained. Findings showed that compatibility and complexity were significant in predicting attitude in regard to switching channel from Internet to brick and mortar store. Relative advantage and compatibility were relevant in predicting attitude in brick and mortar store channel. Attitude also significantly affected channel switching intention regarding to both channels. Our findings reveal that gender and intention significantly affect channel switching behavior.

  20. A Newton Algorithm for Multivariate Total Least Squares Problems

    Directory of Open Access Journals (Sweden)

    WANG Leyang

    2016-04-01

    Full Text Available In order to improve calculation efficiency of parameter estimation, an algorithm for multivariate weighted total least squares adjustment based on Newton method is derived. The relationship between the solution of this algorithm and that of multivariate weighted total least squares adjustment based on Lagrange multipliers method is analyzed. According to propagation of cofactor, 16 computational formulae of cofactor matrices of multivariate total least squares adjustment are also listed. The new algorithm could solve adjustment problems containing correlation between observation matrix and coefficient matrix. And it can also deal with their stochastic elements and deterministic elements with only one cofactor matrix. The results illustrate that the Newton algorithm for multivariate total least squares problems could be practiced and have higher convergence rate.

  1. MIDPOINT TWO- STEPS RULE FOR THE SQUARE ROOT METHOD

    African Journals Online (AJOL)

    DR S.E UWAMUSI

    Aberth third order method for finding zeros of a polynomial in interval ... KEY WORDS: Square root iteration, midpoint two steps Method, ...... A New set of Methods for the simultaneous determination of zeros of polynomial equation and iterative ...

  2. Chi-square test and its application in hypothesis testing

    Directory of Open Access Journals (Sweden)

    Rakesh Rana

    2015-01-01

    Full Text Available In medical research, there are studies which often collect data on categorical variables that can be summarized as a series of counts. These counts are commonly arranged in a tabular format known as a contingency table. The chi-square test statistic can be used to evaluate whether there is an association between the rows and columns in a contingency table. More specifically, this statistic can be used to determine whether there is any difference between the study groups in the proportions of the risk factor of interest. Chi-square test and the logic of hypothesis testing were developed by Karl Pearson. This article describes in detail what is a chi-square test, on which type of data it is used, the assumptions associated with its application, how to manually calculate it and how to make use of an online calculator for calculating the Chi-square statistics and its associated P-value.

  3. Bounded Perturbation Regularization for Linear Least Squares Estimation

    KAUST Repository

    Ballal, Tarig; Suliman, Mohamed Abdalla Elhag; Al-Naffouri, Tareq Y.

    2017-01-01

    This paper addresses the problem of selecting the regularization parameter for linear least-squares estimation. We propose a new technique called bounded perturbation regularization (BPR). In the proposed BPR method, a perturbation with a bounded

  4. Multi-source least-squares migration of marine data

    KAUST Repository

    Wang, Xin; Schuster, Gerard T.

    2012-01-01

    Kirchhoff based multi-source least-squares migration (MSLSM) is applied to marine streamer data. To suppress the crosstalk noise from the excitation of multiple sources, a dynamic encoding function (including both time-shifts and polarity changes

  5. Squaring the Circle: Attempting Peace in Northern Ireland

    National Research Council Canada - National Science Library

    Marchi, Gina

    1997-01-01

    Finding a political framework for self-government in Northern Ireland that will be supported by both nationalists and unionists is referred to as a modern day attempt to do the impossible-to 'square the circle...

  6. Latin Square Thue-Morse Sequences are Overlap-Free

    Directory of Open Access Journals (Sweden)

    Christopher Robinson Tompkins

    2007-01-01

    Full Text Available We define a morphism based upon a Latin square that generalizes the Thue-Morse morphism. We prove that fixed points of this morphism are overlap-free sequences, generalizing results of Allouche - Shallit and Frid.

  7. Suppression of vortex shedding around a square cylinder using ...

    Indian Academy of Sciences (India)

    control of vortex shedding of square cylinders using blowing or suction. ... also showed complete suppression of vortex shedding if suction velocity falls between 0.40 .... equations such that mass balance (continuity) is satisfied simultaneously.

  8. Regularized plane-wave least-squares Kirchhoff migration

    KAUST Repository

    Wang, Xin; Dai, Wei; Schuster, Gerard T.

    2013-01-01

    A Kirchhoff least-squares migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images. A regularization term is included that accounts for mispositioning of reflectors due to errors in the velocity

  9. Improved linear least squares estimation using bounded data uncertainty

    KAUST Repository

    Ballal, Tarig

    2015-04-01

    This paper addresses the problemof linear least squares (LS) estimation of a vector x from linearly related observations. In spite of being unbiased, the original LS estimator suffers from high mean squared error, especially at low signal-to-noise ratios. The mean squared error (MSE) of the LS estimator can be improved by introducing some form of regularization based on certain constraints. We propose an improved LS (ILS) estimator that approximately minimizes the MSE, without imposing any constraints. To achieve this, we allow for perturbation in the measurement matrix. Then we utilize a bounded data uncertainty (BDU) framework to derive a simple iterative procedure to estimate the regularization parameter. Numerical results demonstrate that the proposed BDU-ILS estimator is superior to the original LS estimator, and it converges to the best linear estimator, the linear-minimum-mean-squared error estimator (LMMSE), when the elements of x are statistically white.

  10. Plane-wave Least-squares Reverse Time Migration

    KAUST Repository

    Dai, Wei; Schuster, Gerard T.

    2012-01-01

    convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A

  11. 3D plane-wave least-squares Kirchhoff migration

    KAUST Repository

    Wang, Xin; Dai, Wei; Huang, Yunsong; Schuster, Gerard T.

    2014-01-01

    A three dimensional least-squares Kirchhoff migration (LSM) is developed in the prestack plane-wave domain to increase the quality of migration images and the computational efficiency. Due to the limitation of current 3D marine acquisition

  12. Making the most out of least-squares migration

    KAUST Repository

    Huang, Yunsong; Dutta, Gaurav; Dai, Wei; Wang, Xin; Schuster, Gerard T.; Yu, Jianhua

    2014-01-01

    ) weak amplitudes resulting from geometric spreading, attenuation, and defocusing. These problems can be remedied in part by least-squares migration (LSM), also known as linearized seismic inversion or migration deconvolution (MD), which aims to linearly

  13. Making the most out of the least (squares migration)

    KAUST Repository

    Dutta, Gaurav; Huang, Yunsong; Dai, Wei; Wang, Xin; Schuster, Gerard T.

    2014-01-01

    ) ringiness caused by a ringy source wavelet. To partly remedy these problems, least-squares migration (LSM), also known as linearized seismic inversion or migration deconvolution (MD), proposes to linearly invert seismic data for the reflectivity distribution

  14. Least squares analysis of fission neutron standard fields

    International Nuclear Information System (INIS)

    Griffin, P.J.; Williams, J.G.

    1997-01-01

    A least squares analysis of fission neutron standard fields has been performed using the latest dosimetry cross sections. Discrepant nuclear data are identified and adjusted spectra for 252 Cf spontaneous fission and 235 U thermal fission fields are presented

  15. On square-free edge colorings of graphs

    DEFF Research Database (Denmark)

    Barat, Janos; Varju, P.P.

    2008-01-01

    An edge coloring of a graph is called square-free, if the sequence of colors on certain walks is not a square, that is not of the form x(1,)...,x(m), x(1),...,x(m), for any m epsilon N. Recently, various classes of walks have been suggested to be considered in the above definition. We construct...... graphs, for which the minimum number of colors needed for a square-free coloring is different if the considered set of walks vary, solving a problem posed by Bre ar and Klav2ar. We also prove the following: if an edge coloring of G is not square-free (even in the most general sense), then the length...

  16. Improved linear least squares estimation using bounded data uncertainty

    KAUST Repository

    Ballal, Tarig; Al-Naffouri, Tareq Y.

    2015-01-01

    This paper addresses the problemof linear least squares (LS) estimation of a vector x from linearly related observations. In spite of being unbiased, the original LS estimator suffers from high mean squared error, especially at low signal-to-noise ratios. The mean squared error (MSE) of the LS estimator can be improved by introducing some form of regularization based on certain constraints. We propose an improved LS (ILS) estimator that approximately minimizes the MSE, without imposing any constraints. To achieve this, we allow for perturbation in the measurement matrix. Then we utilize a bounded data uncertainty (BDU) framework to derive a simple iterative procedure to estimate the regularization parameter. Numerical results demonstrate that the proposed BDU-ILS estimator is superior to the original LS estimator, and it converges to the best linear estimator, the linear-minimum-mean-squared error estimator (LMMSE), when the elements of x are statistically white.

  17. A new stabilized least-squares imaging condition

    International Nuclear Information System (INIS)

    Vivas, Flor A; Pestana, Reynam C; Ursin, Bjørn

    2009-01-01

    The classical deconvolution imaging condition consists of dividing the upgoing wave field by the downgoing wave field and summing over all frequencies and sources. The least-squares imaging condition consists of summing the cross-correlation of the upgoing and downgoing wave fields over all frequencies and sources, and dividing the result by the total energy of the downgoing wave field. This procedure is more stable than using the classical imaging condition, but it still requires stabilization in zones where the energy of the downgoing wave field is small. To stabilize the least-squares imaging condition, the energy of the downgoing wave field is replaced by its average value computed in a horizontal plane in poorly illuminated regions. Applications to the Marmousi and Sigsbee2A data sets show that the stabilized least-squares imaging condition produces better images than the least-squares and cross-correlation imaging conditions

  18. Ion channelling in diamond

    International Nuclear Information System (INIS)

    Derry, T.E.

    1978-06-01

    Diamond is one of the most extreme cases from a channelling point of view, having the smallest thermal vibration amplitude and the lowest atomic number of commonly-encountered crystals. These are the two parameters most important for determining channelling behaviour. It is of consiberable interest therefore to see how well the theories explaining and predicting the channeling properties of other substance, succeed with diamond. Natural diamond, although the best available form for these experiments, is rather variable in its physical properties. Part of the project was devoted to considering and solving the problem of obtaining reproducible results representative of the ideal crystal. Channelling studies were performed on several good crystals, using the Rutherford backscattering method. Critical angles for proton channelling were measured for incident energies from 0.6 to 4.5 MeV, in the three most open axes and three most open planes of the diamond structure, and for α-particle channelling at 0.7 and 1.0 MeV (He + ) in the same axes and planes. For 1.0 MeV protons, the crystal temperature was varied from 20 degrees Celsius to 700 degrees Celsius. The results are presented as curves of backscattered yield versus angle in the region of each axis or plane, and summarised in the form of tables and graphs. Generally the critical angles, axial minimum yields, and temperature dependence are well predicted by the accepted theories. The most valuable overall conclusion is that the mean thermal vibration amplitude of the atoms in a crytical determines the critical approach distance to the channel walls at which an ion can remain channelled, even when this distance is much smaller than the Thomas-Fermi screening distance of the atomic potential, as is the case in diamond. A brief study was made of the radiation damage caused by α-particle bombardment, via its effect on the channelling phenomenon. It was possible to hold damage down to negligible levels during the

  19. Approximating the constellation constrained capacity of the MIMO channel with discrete input

    DEFF Research Database (Denmark)

    Yankov, Metodi Plamenov; Forchhammer, Søren; Larsen, Knud J.

    2015-01-01

    In this paper the capacity of a Multiple Input Multiple Output (MIMO) channel is considered, subject to average power constraint, for multi-dimensional discrete input, in the case when no channel state information is available at the transmitter. We prove that when the constellation size grows, t...... for the equivalent orthogonal channel, obtained by the singular value decomposition. Furthermore, lower bounds on the constrained capacity are derived for the cases of square and tall MIMO matrix, by optimizing the constellation for the equivalent channel, obtained by QR decomposition....

  20. Distributive estimation of frequency selective channels for massive MIMO systems

    KAUST Repository

    Zaib, Alam

    2015-12-28

    We consider frequency selective channel estimation in the uplink of massive MIMO-OFDM systems, where our major concern is complexity. A low complexity distributed LMMSE algorithm is proposed that attains near optimal channel impulse response (CIR) estimates from noisy observations at receive antenna array. In proposed method, every antenna estimates the CIRs of its neighborhood followed by recursive sharing of estimates with immediate neighbors. At each step, every antenna calculates the weighted average of shared estimates which converges to near optimal LMMSE solution. The simulation results validate the near optimal performance of proposed algorithm in terms of mean square error (MSE). © 2015 EURASIP.

  1. Perception of Length to Width Relations of City Squares

    Directory of Open Access Journals (Sweden)

    Harold T. Nefs

    2013-04-01

    Full Text Available In this paper, we focus on how people perceive the aspect ratio of city squares. Earlier research has focused on distance perception but not so much on the perceived aspect ratio of the surrounding space. Furthermore, those studies have focused on “open” spaces rather than urban areas enclosed by walls, houses and filled with people, cars, etc. In two experiments, we therefore measured, using a direct and an indirect method, the perceived aspect ratio of five city squares in the historic city center of Delft, the Netherlands. We also evaluated whether the perceived aspect ratio of city squares was affected by the position of the observer on the square. In the first experiment, participants were asked to set the aspect ratio of a small rectangle such that it matched the perceived aspect ratio of the city square. In the second experiment, participants were asked to estimate the length and width of the city square separately. In the first experiment, we found that the perceived aspect ratio was in general lower than the physical aspect ratio. However, in the second experiment, we found that the calculated ratios were close to veridical except for the most elongated city square. We conclude therefore that the outcome depends on how the measurements are performed. Furthermore, although indirect measurements are nearly veridical, the perceived aspect ratio is an underestimation of the physical aspect ratio when measured in a direct way. Moreover, the perceived aspect ratio also depends on the location of the observer. These results may be beneficial to the design of large open urban environments, and in particular to rectangular city squares.

  2. Consistency of the least weighted squares under heteroscedasticity

    Czech Academy of Sciences Publication Activity Database

    Víšek, Jan Ámos

    2011-01-01

    Roč. 2011, č. 47 (2011), s. 179-206 ISSN 0023-5954 Grant - others:GA UK(CZ) GA402/09/055 Institutional research plan: CEZ:AV0Z10750506 Keywords : Regression * Consistency * The least weighted squares * Heteroscedasticity Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.454, year: 2011 http://library.utia.cas.cz/separaty/2011/SI/visek-consistency of the least weighted squares under heteroscedasticity.pdf

  3. Behaviour of FRP confined concrete in square columns

    OpenAIRE

    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...

  4. A Simple Square Rooting Circuit Based on Operational Amplifiers (OPAMPs

    Directory of Open Access Journals (Sweden)

    K. C. Selvam

    2013-02-01

    Full Text Available A simple circuit which accepts a negative voltage as input and provides an output voltage equal to the square root of the input voltage is described in this paper. The square rooting operation is dependent only on the ratio of two resistors and a DC voltage. Hence, the required accuracy can be obtained by employing precision resistors and a stable reference voltage. The feasibility of the circuit is examined by testing the results on a proto type.

  5. Analisa Faktor Pembentuk Kualitas Layanan Di Starbucks the Square Surabaya

    OpenAIRE

    Tanujaya, Jimmy

    2013-01-01

    — Starbucks merupakan salah satu Perusahaan yang bergerak dibidang kedai kopi. Disini peneliti ingin meneliti faktor-faktor apa saja yang membentuk kualitas layanan di Starbucks The Square.Penelitian ini dilakukan untuk mengetahui dan menganalisis faktor apa saja yang membentuk kualitas layanan di Starbucks. Penelitian ini menggunakan jenis penelitian kuantitatif yang bertujuan untuk menganalisis faktor-faktor yang membentuk kualitas layanan di Starbucks The Square dengan menggunakan kuesion...

  6. A Generalized Autocovariance Least-Squares Method for Covariance Estimation

    DEFF Research Database (Denmark)

    Åkesson, Bernt Magnus; Jørgensen, John Bagterp; Poulsen, Niels Kjølstad

    2007-01-01

    A generalization of the autocovariance least- squares method for estimating noise covariances is presented. The method can estimate mutually correlated system and sensor noise and can be used with both the predicting and the filtering form of the Kalman filter.......A generalization of the autocovariance least- squares method for estimating noise covariances is presented. The method can estimate mutually correlated system and sensor noise and can be used with both the predicting and the filtering form of the Kalman filter....

  7. Mean Square Synchronization of Stochastic Nonlinear Delayed Coupled Complex Networks

    Directory of Open Access Journals (Sweden)

    Chengrong Xie

    2013-01-01

    Full Text Available We investigate the problem of adaptive mean square synchronization for nonlinear delayed coupled complex networks with stochastic perturbation. Based on the LaSalle invariance principle and the properties of the Weiner process, the controller and adaptive laws are designed to ensure achieving stochastic synchronization and topology identification of complex networks. Sufficient conditions are given to ensure the complex networks to be mean square synchronization. Furthermore, numerical simulations are also given to demonstrate the effectiveness of the proposed scheme.

  8. Nuclear design analysis of square-lattice honeycomb space nuclear rocket engine

    International Nuclear Information System (INIS)

    Widargo, Reza; Anghaie, Samim

    1999-01-01

    The square-lattice honeycomb reactor is designed based on a cylindrical core that is determined to have critical diameter and length of 0.50 m and 0.50 c, respectively. A 0.10-cm thick radial graphite reflector, in addition to a 0.20-m thick axial graphite reflector are used to reduce neutron leakage from the reactor. The core is fueled with solid solution of 93% enriched (U, Zr, Nb)C, which is one of several ternary uranium carbides that are considered for this concept. The fuel is to be fabricated as 2 mm grooved (U, Zr, Nb)C wafers. The fuel wafers are used to form square-lattice honeycomb fuel assemblies, 0.10 m in length with 30% cross-sectional flow area. Five fuel assemblies are stacked up axially to form the reactor core. Based on the 30% void fraction, the width of the square flow channel is about 1.3 mm. The hydrogen propellant is passed through these flow channels and removes the heat from the reactor core. To perform nuclear design analysis, a series of neutron transport and diffusion codes are used. The preliminary results are obtained using a simple four-group cross-section model. To optimize the nuclear design, the fuel densities are varied for each assembly. Tantalum, hafnium and tungsten are considered and used as a replacement for niobium in fuel material to provide water submersion sub-criticality for the reactor. Axial and radial neutron flux and power density distributions are calculated for the core. Results of the neutronic analysis indicate that the core has a relatively fast spectrum. From the results of the thermal hydraulic analyses, eight axial temperature zones are chosen for the calculation of group average cross-sections. An iterative process is conducted to couple the neutronic calculations with the thermal hydraulics calculations. Results of the nuclear design analysis indicate that a compact core can be designed based on ternary uranium carbide square-lattice honeycomb fuel. This design provides a relatively high thrust to weight

  9. Optical Communications Channel Combiner

    Science.gov (United States)

    Quirk, Kevin J.; Quirk, Kevin J.; Nguyen, Danh H.; Nguyen, Huy

    2012-01-01

    NASA has identified deep-space optical communications links as an integral part of a unified space communication network in order to provide data rates in excess of 100 Mb/s. The distances and limited power inherent in a deep-space optical downlink necessitate the use of photon-counting detectors and a power-efficient modulation such as pulse position modulation (PPM). For the output of each photodetector, whether from a separate telescope or a portion of the detection area, a communication receiver estimates a log-likelihood ratio for each PPM slot. To realize the full effective aperture of these receivers, their outputs must be combined prior to information decoding. A channel combiner was developed to synchronize the log-likelihood ratio (LLR) sequences of multiple receivers, and then combines these into a single LLR sequence for information decoding. The channel combiner synchronizes the LLR sequences of up to three receivers and then combines these into a single LLR sequence for output. The channel combiner has three channel inputs, each of which takes as input a sequence of four-bit LLRs for each PPM slot in a codeword via a XAUI 10 Gb/s quad optical fiber interface. The cross-correlation between the channels LLR time series are calculated and used to synchronize the sequences prior to combining. The output of the channel combiner is a sequence of four-bit LLRs for each PPM slot in a codeword via a XAUI 10 Gb/s quad optical fiber interface. The unit is controlled through a 1 Gb/s Ethernet UDP/IP interface. A deep-space optical communication link has not yet been demonstrated. This ground-station channel combiner was developed to demonstrate this capability and is unique in its ability to process such a signal.

  10. Temperature fields induced by direct contact condensation of steam in a cross-flow in a channel

    NARCIS (Netherlands)

    Clerx, N.; van Deurzen, L.G.M.; Pecenko, A.; Liew, R.; van der Geld, C.W.M.; Kuerten, Johannes G.M.

    2011-01-01

    The temperature fields in the center plane of a channel with a square cross-section have been measured. Steam injected at relatively low mass fluxes through a small hole in one of the walls of the channel condensed intermittently in a small area close to the inlet. The upstream temperature of the

  11. Channel Choice: A Literature Review

    DEFF Research Database (Denmark)

    Østergaard Madsen, Christian; Kræmmergaard, Pernille

    2015-01-01

    The channel choice branch of e-government studies citizens’ and businesses’ choice of channels for interacting with government, and how government organizations can integrate channels and migrate users towards the most cost-efficient channels. In spite of the valuable contributions offered...

  12. Channel Identification Machines

    Directory of Open Access Journals (Sweden)

    Aurel A. Lazar

    2012-01-01

    Full Text Available We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

  13. Channel identification machines.

    Science.gov (United States)

    Lazar, Aurel A; Slutskiy, Yevgeniy B

    2012-01-01

    We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s) onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS) with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

  14. An Adaptive Channel Estimation Algorithm Using Time-Frequency Polynomial Model for OFDM with Fading Multipath Channels

    Directory of Open Access Journals (Sweden)

    Liu KJ Ray

    2002-01-01

    Full Text Available Orthogonal frequency division multiplexing (OFDM is an effective technique for the future 3G communications because of its great immunity to impulse noise and intersymbol interference. The channel estimation is a crucial aspect in the design of OFDM systems. In this work, we propose a channel estimation algorithm based on a time-frequency polynomial model of the fading multipath channels. The algorithm exploits the correlation of the channel responses in both time and frequency domains and hence reduce more noise than the methods using only time or frequency polynomial model. The estimator is also more robust compared to the existing methods based on Fourier transform. The simulation shows that it has more than improvement in terms of mean-squared estimation error under some practical channel conditions. The algorithm needs little prior knowledge about the delay and fading properties of the channel. The algorithm can be implemented recursively and can adjust itself to follow the variation of the channel statistics.

  15. Cryogenic microwave channelized receiver

    International Nuclear Information System (INIS)

    Rauscher, C.; Pond, J.M.; Tait, G.B.

    1996-01-01

    The channelized receiver being presented demonstrates the use of high temperature superconductor technology in a microwave system setting where superconductor, microwave-monolithic-integrated-circuit, and hybrid-integrated-circuit components are united in one package and cooled to liquid-nitrogen temperatures. The receiver consists of a superconducting X-band four-channel demultiplexer with 100-MHz-wide channels, four commercial monolithically integrated mixers, and four custom-designed hybrid-circuit detectors containing heterostructure ramp diodes. The composite receiver unit has been integrated into the payload of the second-phase NRL high temperature superconductor space experiment (HTSSE-II). Prior to payload assembly, the response characteristics of the receiver were measured as functions of frequency, temperature, and drive levels. The article describes the circuitry, discusses the key issues related to design and implementation, and summarizes the experimental results

  16. Chaos in quantum channels

    Energy Technology Data Exchange (ETDEWEB)

    Hosur, Pavan; Qi, Xiao-Liang [Department of Physics, Stanford University,476 Lomita Mall, Stanford, California 94305 (United States); Roberts, Daniel A. [Center for Theoretical Physics and Department of Physics, Massachusetts Institute of Technology,77 Massachusetts Ave, Cambridge, Massachusetts 02139 (United States); Yoshida, Beni [Perimeter Institute for Theoretical Physics,31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada); Walter Burke Institute for Theoretical Physics, California Institute of Technology,1200 E California Blvd, Pasadena CA 91125 (United States)

    2016-02-01

    We study chaos and scrambling in unitary channels by considering their entanglement properties as states. Using out-of-time-order correlation functions to diagnose chaos, we characterize the ability of a channel to process quantum information. We show that the generic decay of such correlators implies that any input subsystem must have near vanishing mutual information with almost all partitions of the output. Additionally, we propose the negativity of the tripartite information of the channel as a general diagnostic of scrambling. This measures the delocalization of information and is closely related to the decay of out-of-time-order correlators. We back up our results with numerics in two non-integrable models and analytic results in a perfect tensor network model of chaotic time evolution. These results show that the butterfly effect in quantum systems implies the information-theoretic definition of scrambling.

  17. Direct numerical simulation of free and forced square jets

    International Nuclear Information System (INIS)

    Gohil, Trushar B.; Saha, Arun K.; Muralidhar, K.

    2015-01-01

    Highlights: • Free square jet at Re = 500–2000 is studied using DNS. • Forced square jet at Re = 1000 subjected to varicose perturbation is also investigated at various forcing frequencies. • Vortex interactions within the jet and jet spreading are affected both for free and forced jets. • Perturbation at higher frequency shows axis-switching. - Abstract: Direct numerical simulation (DNS) of incompressible, spatially developing square jets in the Reynolds number range of 500–2000 is reported. The three-dimensional unsteady Navier–Stokes equations are solved using high order spatial and temporal discretization. The objective of the present work is to understand the evolution of free and forced square jets by examining the formation of large-scale structures. Coherent structures and related interactions of free jets suggest control strategies that can be used to achieve enhanced spreading and mixing of the jet with the surrounding fluid. The critical Reynolds number for the onset on unsteadiness in an unperturbed free square jet is found to be 875–900 while it reduces to the range 500–525 in the presence of small-scale perturbations. Disturbances applied at the flow inlet cause saturation of KH-instability and early transition to turbulence. Forced jet calculations have been carried out using varicose perturbation with amplitude of 15%, while frequency is independently varied. Simulations show that the initial development of the square jet is influenced by the four corners leading to the appearance hairpin structures along with the formation of vortex rings. Farther downstream, adjacent vortices strongly interact leading to their rapid breakup. Excitation frequencies in the range 0.4–0.6 cause axis-switching of the jet cross-section. Results show that square jets achieve greater spreading but are less controllable in comparison to the circular ones

  18. Distribution Channels Conflict and Management

    OpenAIRE

    Kiran, Dr Vasanth; Majumdar, Dr Mousumi; Kishore, Dr Krishna

    2012-01-01

    Relationships in distribution channels tend to be long-term oriented and members of the channel rely on each other to jointly realize their goals by serving buyers. Despite the channels focus on serving buyers, conflicts often arise between channel members because of each members self-interest. When conflicts arise, the perceptions of a channel member based on normative, rational/instrumental, or emotional reasoning will influence relational norms like trust and commitment that characterize t...

  19. A library least-squares approach for scatter correction in gamma-ray tomography

    Science.gov (United States)

    Meric, Ilker; Anton Johansen, Geir; Valgueiro Malta Moreira, Icaro

    2015-03-01

    Scattered radiation is known to lead to distortion in reconstructed images in Computed Tomography (CT). The effects of scattered radiation are especially more pronounced in non-scanning, multiple source systems which are preferred for flow imaging where the instantaneous density distribution of the flow components is of interest. In this work, a new method based on a library least-squares (LLS) approach is proposed as a means of estimating the scatter contribution and correcting for this. The validity of the proposed method is tested using the 85-channel industrial gamma-ray tomograph previously developed at the University of Bergen (UoB). The results presented here confirm that the LLS approach can effectively estimate the amounts of transmission and scatter components in any given detector in the UoB gamma-ray tomography system.

  20. Multi-channel unidirectional transmission of phononic crystal heterojunctions

    Science.gov (United States)

    Xu, Zhenlong; Tong, Jie; Wu, Fugen

    2018-02-01

    Two square steel columns are arranged in air to form two-dimensional square lattice phononic crystals (PNCs). Two PNCs can be combined into a non-orthogonal 45∘ heterojunction when the difference in the directional band gaps of the two PNC types is utilized. The finite element method is used to calculate the acoustic band structure, the heterogeneous junction transmission characteristics, acoustic field distribution, and many others. Results show that a non-orthogonal PNC heterojunction can produce a multi-channel unidirectional transmission of acoustic waves. With the square scatterer rotated, the heterojunction can select a frequency band for unidirectional transmission performance. This capability is particularly useful for constructing acoustic diodes with wide-bands and high-efficiency unidirectional transmission characteristics.

  1. Fuel channel refilling

    International Nuclear Information System (INIS)

    Shoukri, M.; Abdul-Razzak, A.

    1992-11-01

    This report extends the work reported in document INFO-0370 on fuel channel refilling by providing analysis of the refilling tests conducted using the RD-14 and RD-14M test facilities. The analysis focuses on the general thermal-hydraulic characteristics of the facilities following various small and large inlet and outlet header breaks with emergency coolant injection. The two-fluid model thermal-hydraulic computer code CATHENA was tested against results obtained from selected experiments carried out in the two facilities. Conclusions related to the effect of break size, mode of emergency core injection, primary pump operation and parallel channels are presented. (Author) (116 figs., 17 tabs., 53 refs.)

  2. Ion channels in glioblastoma.

    Science.gov (United States)

    Molenaar, Remco J

    2011-01-01

    Glioblastoma is the most common primary brain tumor with the most dismal prognosis. It is characterized by extensive invasion, migration, and angiogenesis. Median survival is only 15 months due to this behavior, rendering focal surgical resection ineffective and adequate radiotherapy impossible. At this moment, several ion channels have been implicated in glioblastoma proliferation, migration, and invasion. This paper summarizes studies on potassium, sodium, chloride, and calcium channels of glioblastoma. It provides an up-to-date overview of the literature that could ultimately lead to new therapeutic targets.

  3. Fuel channel refilling

    International Nuclear Information System (INIS)

    Shoukri, M.; Abdul-Razzak, A.

    1990-04-01

    Analysis of existing data on fuel channel refilling is presented. The analysis focuses on the data obtained using the Stern Laboratories Cold Water Injection Test (CWIT) Facility. The two-fluid model thermal-hydraulics computer code CATHENA is also used to simulate experimental results on fuel channel refilling from both the CWIT and RD-14 facilities. Conclusions related to single and double break tests, including the effect of non-condensible gases, are presented. A set of recommendations is given for further analysis and separate effect experiments. (67 figs., 5 tabs., 24 refs.)

  4. On squares of representations of compact Lie algebras

    Energy Technology Data Exchange (ETDEWEB)

    Zeier, Robert, E-mail: robert.zeier@ch.tum.de [Department Chemie, Technische Universität München, Lichtenbergstrasse 4, 85747 Garching (Germany); Zimborás, Zoltán, E-mail: zimboras@gmail.com [Department of Computer Science, University College London, Gower St., London WC1E 6BT (United Kingdom)

    2015-08-15

    We study how tensor products of representations decompose when restricted from a compact Lie algebra to one of its subalgebras. In particular, we are interested in tensor squares which are tensor products of a representation with itself. We show in a classification-free manner that the sum of multiplicities and the sum of squares of multiplicities in the corresponding decomposition of a tensor square into irreducible representations has to strictly grow when restricted from a compact semisimple Lie algebra to a proper subalgebra. For this purpose, relevant details on tensor products of representations are compiled from the literature. Since the sum of squares of multiplicities is equal to the dimension of the commutant of the tensor-square representation, it can be determined by linear-algebra computations in a scenario where an a priori unknown Lie algebra is given by a set of generators which might not be a linear basis. Hence, our results offer a test to decide if a subalgebra of a compact semisimple Lie algebra is a proper one without calculating the relevant Lie closures, which can be naturally applied in the field of controlled quantum systems.

  5. On squares of representations of compact Lie algebras

    International Nuclear Information System (INIS)

    Zeier, Robert; Zimborás, Zoltán

    2015-01-01

    We study how tensor products of representations decompose when restricted from a compact Lie algebra to one of its subalgebras. In particular, we are interested in tensor squares which are tensor products of a representation with itself. We show in a classification-free manner that the sum of multiplicities and the sum of squares of multiplicities in the corresponding decomposition of a tensor square into irreducible representations has to strictly grow when restricted from a compact semisimple Lie algebra to a proper subalgebra. For this purpose, relevant details on tensor products of representations are compiled from the literature. Since the sum of squares of multiplicities is equal to the dimension of the commutant of the tensor-square representation, it can be determined by linear-algebra computations in a scenario where an a priori unknown Lie algebra is given by a set of generators which might not be a linear basis. Hence, our results offer a test to decide if a subalgebra of a compact semisimple Lie algebra is a proper one without calculating the relevant Lie closures, which can be naturally applied in the field of controlled quantum systems

  6. Sound field simulation and acoustic animation in urban squares

    Science.gov (United States)

    Kang, Jian; Meng, Yan

    2005-04-01

    Urban squares are important components of cities, and the acoustic environment is important for their usability. While models and formulae for predicting the sound field in urban squares are important for their soundscape design and improvement, acoustic animation tools would be of great importance for designers as well as for public participation process, given that below a certain sound level, the soundscape evaluation depends mainly on the type of sounds rather than the loudness. This paper first briefly introduces acoustic simulation models developed for urban squares, as well as empirical formulae derived from a series of simulation. It then presents an acoustic animation tool currently being developed. In urban squares there are multiple dynamic sound sources, so that the computation time becomes a main concern. Nevertheless, the requirements for acoustic animation in urban squares are relatively low compared to auditoria. As a result, it is important to simplify the simulation process and algorithms. Based on a series of subjective tests in a virtual reality environment with various simulation parameters, a fast simulation method with acceptable accuracy has been explored. [Work supported by the European Commission.

  7. Potassium channels in brain mitochondria.

    Science.gov (United States)

    Bednarczyk, Piotr

    2009-01-01

    Potassium channels are the most widely distributed class of ion channels. These channels are transmembrane proteins known to play important roles in both normal and pathophysiological functions in all cell types. Various potassium channels are recognised as potential therapeutic targets in the treatment of Parkinson's disease, Alzheimer's disease, brain/spinal cord ischaemia and sepsis. In addition to their importance as therapeutic targets, certain potassium channels are known for their beneficial roles in anaesthesia, cardioprotection and neuroprotection. Some types of potassium channels present in the plasma membrane of various cells have been found in the inner mitochondrial membrane as well. Potassium channels have been proposed to regulate mitochondrial membrane potential, respiration, matrix volume and Ca(+) ion homeostasis. It has been proposed that mitochondrial potassium channels mediate ischaemic preconditioning in various tissues. However, the specificity of a pharmacological agents and the mechanisms underlying their effects on ischaemic preconditioning remain controversial. The following potassium channels from various tissues have been identified in the inner mitochondrial membrane: ATP-regulated (mitoK(ATP)) channel, large conductance Ca(2+)-regulated (mitoBK(Ca)) channel, intermediate conductance Ca(2+)-regulated (mitoIK(Ca)) channel, voltage-gated (mitoKv1.3 type) channel, and twin-pore domain (mitoTASK-3) channel. It has been shown that increased potassium flux into brain mitochondria induced by either the mitoK(ATP) channel or mitoBK(Ca) channel affects the beneficial effects on neuronal cell survival under pathological conditions. Recently, differential distribution of mitoBK(Ca) channels has been observed in neuronal mitochondria. These findings may suggest a neuroprotective role for the mitoBK(Ca) channel in specific brain structures. This minireview summarises current data on brain mitochondrial potassium channels and the efforts to identify

  8. Equalization of Loudspeaker and Room Responses Using Kautz Filters: Direct Least Squares Design

    Directory of Open Access Journals (Sweden)

    Karjalainen Matti

    2007-01-01

    Full Text Available DSP-based correction of loudspeaker and room responses is becoming an important part of improving sound reproduction. Such response equalization (EQ is based on using a digital filter in cascade with the reproduction channel to counteract the response errors introduced by loudspeakers and room acoustics. Several FIR and IIR filter design techniques have been proposed for equalization purposes. In this paper we investigate Kautz filters, an interesting class of IIR filters, from the point of view of direct least squares EQ design. Kautz filters can be seen as generalizations of FIR filters and their frequency-warped counterparts. They provide a flexible means to obtain desired frequency resolution behavior, which allows low filter orders even for complex corrections. Kautz filters have also the desirable property to avoid inverting dips in transfer function to sharp and long-ringing resonances in the equalizer. Furthermore, the direct least squares design is applicable to nonminimum-phase EQ design and allows using a desired target response. The proposed method is demonstrated by case examples with measured and synthetic loudspeaker and room responses.

  9. Effect of Aspect Ratio, Channel Orientation, Rib Pitch-to-Height Ratio, and Number of Ribbed Walls on Pressure Drop Characteristics in a Rotating Channel with Detached Ribs

    Directory of Open Access Journals (Sweden)

    K. Arun

    2007-01-01

    Full Text Available The present work involves experimental investigation of the effects of aspect ratio, channel orientation angle, rib pitch-to-height ratio (P/e, and number of ribbed walls on friction factor in orthogonally rotating channel with detached ribs. The ribs are separated from the base wall to provide a small region of flow between the base wall and the ribs. Experiments have been conducted at Reynolds number ranging from 10000–17000 with rotation numbers varying from 0–0.38. Pitch-to-rib height ratios (P/e of 5 and 10 at constant rib height-to-hydraulic diameter ratio (e/D of 0.1 and a clearance ratio (C/e of 0.38 are considered. The rib angle of attack with respect to mainstream flow is 90∘. The channel orientation at which the ribbed wall becomes trailing surface (pressure side on which the Coriolis force acts is considered as the 0∘ orientation angle. For one-wall ribbed case, channel is oriented from 0∘ to 180∘ about its axis in steps of 30∘ to change the orientation angle. For two-wall ribbed case, the orientation angle is changed from 0∘ to 90∘ in steps of 30∘. Friction factors for the detached ribbed channels are compared with the corresponding attached ribbed channel. It is found that in one-wall detached ribbed channel, increase in the friction factor ratio with the orientation angle is lower for rectangular channel compared to that of square channel for both the pitch-to-rib height ratios of 5 and 10 at a given Reynolds number and rotation number. Friction factor ratios of two-wall detached ribbed rectangular channel are comparable with corresponding two-wall detached ribbed square channel both under stationary and rotating conditions.

  10. MITOCHONDRIAL BKCa CHANNEL

    Directory of Open Access Journals (Sweden)

    Enrique eBalderas

    2015-03-01

    Full Text Available Since its discovery in a glioma cell line 15 years ago, mitochondrial BKCa channel (mitoBKCa has been studied in brain cells and cardiomyocytes sharing general biophysical properties such as high K+ conductance (~300 pS, voltage-dependency and Ca2+-sensitivity. Main advances in deciphering the molecular composition of mitoBKCa have included establishing that it is encoded by the Kcnma1 gene, that a C-terminal splice insert confers mitoBKCa ability to be targeted to cardiac mitochondria, and evidence for its potential coassembly with β subunits. Notoriously, β1 subunit directly interacts with cytochrome c oxidase and mitoBKCa can be modulated by substrates of the respiratory chain. mitoBKCa channel has a central role in protecting the heart from ischemia, where pharmacological activation of the channel impacts the generation of reactive oxygen species and mitochondrial Ca2+ preventing cell death likely by impeding uncontrolled opening of the mitochondrial transition pore. Supporting this view, inhibition of mitoBKCa with Iberiotoxin, enhances cytochrome c release from glioma mitochondria. Many tantalizing questions remain. Some of them are: how is mitoBKCa coupled to the respiratory chain? Does mitoBKCa play non-conduction roles in mitochondria physiology? Which are the functional partners of mitoBKCa? What are the roles of mitoBKCa in other cell types? Answers to these questions are essential to define the impact of mitoBKCa channel in mitochondria biology and disease.

  11. Chemistry in Microfluidic Channels

    Science.gov (United States)

    Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

    2011-01-01

    General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

  12. Workshop on Gas Channels

    Science.gov (United States)

    2013-02-07

    Effect of pressure on gas permeability. In Fish … Different channels or splice variants at different depth.  HRE (hypoxia-response elements): which...proteins unexpectedly have HREs . HIF-1.  Shear stress:  expression of NOS  Are different splice variants used under different conditions?  Size

  13. Least squares reverse time migration of controlled order multiples

    Science.gov (United States)

    Liu, Y.

    2016-12-01

    Imaging using the reverse time migration of multiples generates inherent crosstalk artifacts due to the interference among different order multiples. Traditionally, least-square fitting has been used to address this issue by seeking the best objective function to measure the amplitude differences between the predicted and observed data. We have developed an alternative objective function by decomposing multiples into different orders to minimize the difference between Born modeling predicted multiples and specific-order multiples from observational data in order to attenuate the crosstalk. This method is denoted as the least-squares reverse time migration of controlled order multiples (LSRTM-CM). Our numerical examples demonstrated that the LSRTM-CM can significantly improve image quality compared with reverse time migration of multiples and least-square reverse time migration of multiples. Acknowledgments This research was funded by the National Nature Science Foundation of China (Grant Nos. 41430321 and 41374138).

  14. A note on Dupuy's QJM and new square law

    Directory of Open Access Journals (Sweden)

    G. Geldenhuys

    2003-12-01

    Full Text Available T N Duputy has developed various operations research models in an attempt to quantify lessons that can be learned from military history. We discuss two of his models, the Quantified Judgment Model (QJM, and the "new square law". The QJM was developed by Duputy for the analysis of military operations. We point out mathematical discrepancies in a part of the model and make suggestions to remove these discrepancies. Duputy's new square law is an attempt to modify the well-known Lanchester equations for aimed fire, taking into account some results that were obtained in the QJM. We show that the new square law cannot be accepted as a valid mathematical model of combat attrition.

  15. Closure of the squared Zakharov--Shabat eigenstates

    International Nuclear Information System (INIS)

    Kaup, D.J.

    1976-01-01

    By solution of the inverse scattering problem for a third-order (degenerate) eigenvalue problem, the closure of the squared eigenfunctions of the Zakharov--Shabat equations is found. The question of the completeness of squared eigenstates occurs in many aspects of ''inverse scattering transforms'' (solving nonlinear evolution equations exactly by inverse scattering techniques), as well as in various aspects of the inverse scattering problem. The method used here is quite suggestive as to how one might find the closure of the squared eigenfunctions of other eigenvalue equations, and the strong analogy between these results and the problem of finding the closure of the eigenvectors of a nonself-adjoint matrix is pointed out

  16. High-frequency matrix converter with square wave input

    Science.gov (United States)

    Carr, Joseph Alexander; Balda, Juan Carlos

    2015-03-31

    A device for producing an alternating current output voltage from a high-frequency, square-wave input voltage comprising, high-frequency, square-wave input a matrix converter and a control system. The matrix converter comprises a plurality of electrical switches. The high-frequency input and the matrix converter are electrically connected to each other. The control system is connected to each switch of the matrix converter. The control system is electrically connected to the input of the matrix converter. The control system is configured to operate each electrical switch of the matrix converter converting a high-frequency, square-wave input voltage across the first input port of the matrix converter and the second input port of the matrix converter to an alternating current output voltage at the output of the matrix converter.

  17. Square vortex lattice in p-wave superconductors

    International Nuclear Information System (INIS)

    Shiraishi, J.

    1999-01-01

    Making use of the Ginzburg Landau equation for isotropic p-wave superconductors, we construct the single vortex solution in part analytically. The fourfold symmetry breaking term arising from the tetragonal symmetry distortion of the Fermi surface is crucial, since this term indicates a fourfold distortion of the vortex core somewhat similar to the one found in d-wave superconductors. This fourfold distortion of the vortex core in turn favors the square vortex lattice as observed recently by small angle neutron scattering (SANS) experiment from Sr 2 RuO 4 . We find that the hexagonal vortex lattice at H = H c1 transforms into the square one for H = H cr = 0.26 H c2 . On the other hand the SANS data does not reveal such transition. The square vortex covers everywhere studied by the SANS implying H cr is very close to H c1 . Therefore some improvement in the present model is certainly desirable. (orig.)

  18. The mean squared writhe of alternating random knot diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Diao, Y; Hinson, K [Department of Mathematics and Statistics University of North Carolina at Charlotte, NC 28223 (United States); Ernst, C; Ziegler, U, E-mail: ydiao@uncc.ed [Department of Mathematics and Computer Science, Western Kentucky University, Bowling Green, KY 42101 (United States)

    2010-12-10

    The writhe of a knot diagram is a simple geometric measure of the complexity of the knot diagram. It plays an important role not only in knot theory itself, but also in various applications of knot theory to fields such as molecular biology and polymer physics. The mean squared writhe of any sample of knot diagrams with n crossings is n when for each diagram at each crossing one of the two strands is chosen as the overpass at random with probability one-half. However, such a diagram is usually not minimal. If we restrict ourselves to a minimal knot diagram, then the choice of which strand is the over- or under-strand at each crossing is no longer independent of the neighboring crossings and a larger mean squared writhe is expected for minimal diagrams. This paper explores the effect on the correlation between the mean squared writhe and the diagrams imposed by the condition that diagrams are minimal by studying the writhe of classes of reduced, alternating knot diagrams. We demonstrate that the behavior of the mean squared writhe heavily depends on the underlying space of diagram templates. In particular this is true when the sample space contains only diagrams of a special structure. When the sample space is large enough to contain not only diagrams of a special type, then the mean squared writhe for n crossing diagrams tends to grow linearly with n, but at a faster rate than n, indicating an intrinsic property of alternating knot diagrams. Studying the mean squared writhe of alternating random knot diagrams also provides some insight into the properties of the diagram generating methods used, which is an important area of study in the applications of random knot theory.

  19. The generalization of the exterior square of a Bieberbach group

    Science.gov (United States)

    Masri, Rohaidah; Hassim, Hazzirah Izzati Mat; Sarmin, Nor Haniza; Ali, Nor Muhainiah Mohd; Idrus, Nor'ashiqin Mohd

    2014-06-01

    The exterior square of a group is one of the homological functors which were originated in the homotopy theory. Meanwhile, a Bieberbach group is a torsion free crystallographic group. A Bieberbach group with cyclic point group of order two, C2, of dimension n can be defined as the direct product of that group of the smallest dimension with a free abelian group. Using the group presentation and commutator generating sequence, the exterior square of a Bieberbach group with point group C2 of dimension n is computed.

  20. Chi-squared goodness of fit tests with applications

    CERN Document Server

    Balakrishnan, N; Nikulin, MS

    2013-01-01

    Chi-Squared Goodness of Fit Tests with Applications provides a thorough and complete context for the theoretical basis and implementation of Pearson's monumental contribution and its wide applicability for chi-squared goodness of fit tests. The book is ideal for researchers and scientists conducting statistical analysis in processing of experimental data as well as to students and practitioners with a good mathematical background who use statistical methods. The historical context, especially Chapter 7, provides great insight into importance of this subject with an authoritative author team

  1. Radiation Field of a Square, Helical Beam Antenna

    DEFF Research Database (Denmark)

    Knudsen, Hans Lottrup

    1952-01-01

    square helices are used. Further, in connection with corresponding rigorous formulas for the field from a circular, helical antenna with a uniformly progressing current wave of constant amplitude the present formulas may be used for an investigation of the magnitude of the error introduced in Kraus......' approximate calculation of the field from a circular, helical antenna by replacing this antenna with an ``equivalent'' square helix. This investigation is carried out by means of a numerical example. The investigation shows that Kraus' approximate method of calculation yields results in fair agreement...

  2. Square Van Atta reflector with conducting mounting flame

    DEFF Research Database (Denmark)

    Nielsen, Erik Dragø

    1970-01-01

    A theoretical and numerical analysis of square Van Atta reflectors has been carried out with or without a conducting plate, used for mounting of the antenna elements. The Van Atta reflector investigated has antenna elements which are parallel half-wave dipoles interconnected in pairs by transmiss......A theoretical and numerical analysis of square Van Atta reflectors has been carried out with or without a conducting plate, used for mounting of the antenna elements. The Van Atta reflector investigated has antenna elements which are parallel half-wave dipoles interconnected in pairs...

  3. Multi-source least-squares migration of marine data

    KAUST Repository

    Wang, Xin

    2012-11-04

    Kirchhoff based multi-source least-squares migration (MSLSM) is applied to marine streamer data. To suppress the crosstalk noise from the excitation of multiple sources, a dynamic encoding function (including both time-shifts and polarity changes) is applied to the receiver side traces. Results show that the MSLSM images are of better quality than the standard Kirchhoff migration and reverse time migration images; moreover, the migration artifacts are reduced and image resolution is significantly improved. The computational cost of MSLSM is about the same as conventional least-squares migration, but its IO cost is significantly decreased.

  4. Radiation and viscous dissipation effect on square porous annulus

    Energy Technology Data Exchange (ETDEWEB)

    Badruddin, Irfan Anjum [Dept. of Mechanical Engineering, University of Malaya, Kuala Lumpur, 50603 (Malaysia); Quadir, G. A. [School of Mechatronic Engineering, University Malaysia Perlis, Pauh Putra, 02600 Arau, Perlis (Malaysia)

    2016-06-08

    The present study is carried out to investigate the effect of radiation and viscous dissipation in a square porous annulus subjected to outside hot T{sub h} and inside cold T{sub c} temperature. The square annulus has a hollow section of dimension D×D at the interior of annulus. The flow is assumed to obey Darcy law. The governing equations are non-dimensionalised and solved with the help of finite element method. Results are discussed with respect to viscous dissipation parameter, radiation parameter and size of the hollow section of annulus.

  5. Sparse least-squares reverse time migration using seislets

    KAUST Repository

    Dutta, Gaurav

    2015-08-19

    We propose sparse least-squares reverse time migration (LSRTM) using seislets as a basis for the reflectivity distribution. This basis is used along with a dip-constrained preconditioner that emphasizes image updates only along prominent dips during the iterations. These dips can be estimated from the standard migration image or from the gradient using plane-wave destruction filters or structural tensors. Numerical tests on synthetic datasets demonstrate the benefits of this method for mitigation of aliasing artifacts and crosstalk noise in multisource least-squares migration.

  6. Proportionate-type normalized last mean square algorithms

    CERN Document Server

    Wagner, Kevin

    2013-01-01

    The topic of this book is proportionate-type normalized least mean squares (PtNLMS) adaptive filtering algorithms, which attempt to estimate an unknown impulse response by adaptively giving gains proportionate to an estimate of the impulse response and the current measured error. These algorithms offer low computational complexity and fast convergence times for sparse impulse responses in network and acoustic echo cancellation applications. New PtNLMS algorithms are developed by choosing gains that optimize user-defined criteria, such as mean square error, at all times. PtNLMS algorithms ar

  7. Global Search Strategies for Solving Multilinear Least-Squares Problems

    Directory of Open Access Journals (Sweden)

    Mats Andersson

    2012-04-01

    Full Text Available The multilinear least-squares (MLLS problem is an extension of the linear least-squares problem. The difference is that a multilinear operator is used in place of a matrix-vector product. The MLLS is typically a large-scale problem characterized by a large number of local minimizers. It originates, for instance, from the design of filter networks. We present a global search strategy that allows for moving from one local minimizer to a better one. The efficiency of this strategy is illustrated by the results of numerical experiments performed for some problems related to the design of filter networks.

  8. LSL: a logarithmic least-squares adjustment method

    International Nuclear Information System (INIS)

    Stallmann, F.W.

    1982-01-01

    To meet regulatory requirements, spectral unfolding codes must not only provide reliable estimates for spectral parameters, but must also be able to determine the uncertainties associated with these parameters. The newer codes, which are more appropriately called adjustment codes, use the least squares principle to determine estimates and uncertainties. The principle is simple and straightforward, but there are several different mathematical models to describe the unfolding problem. In addition to a sound mathematical model, ease of use and range of options are important considerations in the construction of adjustment codes. Based on these considerations, a least squares adjustment code for neutron spectrum unfolding has been constructed some time ago and tentatively named LSL

  9. 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.

  10. On a Generalized Squared Gaussian Diffusion Model for Option Valuation

    Directory of Open Access Journals (Sweden)

    Edeki S.O.

    2017-01-01

    Full Text Available In financial mathematics, option pricing models are vital tools whose usefulness cannot be overemphasized. Modern approaches and modelling of financial derivatives are therefore required in option pricing and valuation settings. In this paper, we derive via the application of Ito lemma, a pricing model referred to as Generalized Squared Gaussian Diffusion Model (GSGDM for option pricing and valuation. Same approach can be considered via Stratonovich stochastic dynamics. We also show that the classical Black-Scholes, and the square root constant elasticity of variance models are special cases of the GSGDM. In addition, general solution of the GSGDM is obtained using modified variational iterative method (MVIM.

  11. A decentralized square root information filter/smoother

    Science.gov (United States)

    Bierman, G. J.; Belzer, M. R.

    1985-01-01

    A number of developments has recently led to a considerable interest in the decentralization of linear least squares estimators. The developments are partly related to the impending emergence of VLSI technology, the realization of parallel processing, and the need for algorithmic ways to speed the solution of dynamically decoupled, high dimensional estimation problems. A new method is presented for combining Square Root Information Filters (SRIF) estimates obtained from independent data sets. The new method involves an orthogonal transformation, and an information matrix filter 'homework' problem discussed by Schweppe (1973) is generalized. The employed SRIF orthogonal transformation methodology has been described by Bierman (1977).

  12. Radiation and viscous dissipation effect on square porous annulus

    International Nuclear Information System (INIS)

    Badruddin, Irfan Anjum; Quadir, G. A.

    2016-01-01

    The present study is carried out to investigate the effect of radiation and viscous dissipation in a square porous annulus subjected to outside hot T h and inside cold T c temperature. The square annulus has a hollow section of dimension D×D at the interior of annulus. The flow is assumed to obey Darcy law. The governing equations are non-dimensionalised and solved with the help of finite element method. Results are discussed with respect to viscous dissipation parameter, radiation parameter and size of the hollow section of annulus.

  13. Effective Scheme of Channel Tracking and Estimation for Mobile WiMAX DL-PUSC System

    Directory of Open Access Journals (Sweden)

    Phuong Thi Thu Pham

    2010-01-01

    Full Text Available This paper introduces an effective joint scheme of channel estimation and tracking for downlink partial usage of subchannel (DL-PUSC mode of mobile WiMAX system. Based on the pilot pattern of this particular system, some channel estimation methods including conventional interpolations and a more favorable least-squares line fitting (LSLF technique are comparatively studied. Besides, channel estimation performance can be remarkably improved by taking advantage of channel tracking derived from the preamble symbol. System performances in terms of packet error rate (PER and user link throughput are investigated in various channels adopted from the well-known ITU models for mobile environments. Simulation results show a significant performance enhancement when the proposed joint scheme is utilized, at least 5 dB, compared to only commonly used channel estimation approaches.

  14. Minimum Probability of Error-Based Equalization Algorithms for Fading Channels

    Directory of Open Access Journals (Sweden)

    Janos Levendovszky

    2007-06-01

    Full Text Available Novel channel equalizer algorithms are introduced for wireless communication systems to combat channel distortions resulting from multipath propagation. The novel algorithms are based on newly derived bounds on the probability of error (PE and guarantee better performance than the traditional zero forcing (ZF or minimum mean square error (MMSE algorithms. The new equalization methods require channel state information which is obtained by a fast adaptive channel identification algorithm. As a result, the combined convergence time needed for channel identification and PE minimization still remains smaller than the convergence time of traditional adaptive algorithms, yielding real-time equalization. The performance of the new algorithms is tested by extensive simulations on standard mobile channels.

  15. A Novel Comb-Pilot Transform Domain Frequency Diversity Channel Estimation for OFDM System

    Directory of Open Access Journals (Sweden)

    L. Liu

    2009-12-01

    Full Text Available Due to implementation complexity, the transform domain channel estimation based on training symbols or comb-type pilots has been paid more attention because of its efficient algorithm FFT/IFFT. However, in a comb-type OFDM system, the length of the channel impulse response is much smaller than the pilot number. In this case, the comb-pilot transform domain channel estimation only works as interpolation like the Least Squares (LS algorithm, but loses the noise suppression function. In this paper, we propose a novel frequency diversity channel estimation method via grouped pilots combining. With this estimator, not only the channel frequency response on non-pilot subcarriers can be interpolated, but also the noise can be better suppressed. Moreover, it does not need prior statistical characteristics of the wireless channel.

  16. Heavy-quark pair production in gluon fusion at next-to-next-to-leading O({alpha}{sup 4}{sub s}) order. One-loop squared contributions

    Energy Technology Data Exchange (ETDEWEB)

    Kniehl, B.A.; Merebashvili, Z. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Koerner, J.G. [Mainz Univ. (Germany). Inst. fuer Physik; Rogal, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2008-09-15

    We calculate the next-to-next-to-leading order O({alpha}{sup 4}{sub s}) one-loop squared corrections to the production of heavy quark pairs in the gluon-gluon fusion process. Together with the previously derived results on the q anti q production channel the results of this paper complete the calculation of the oneloop squared contributions of the next-to-next-to-leading order O({alpha}{sup 4}{sub s}) radiative QCD corrections to the hadroproduction of heavy flavours. Our results, with the full mass dependence retained, are presented in a closed and very compact form, in dimensional regularization. (orig.)

  17. Heavy-quark pair production in gluon fusion at next-to-next-to-leading O(α4s) order. One-loop squared contributions

    International Nuclear Information System (INIS)

    Kniehl, B.A.; Merebashvili, Z.

    2008-09-01

    We calculate the next-to-next-to-leading order O(α 4 s ) one-loop squared corrections to the production of heavy quark pairs in the gluon-gluon fusion process. Together with the previously derived results on the q anti q production channel the results of this paper complete the calculation of the oneloop squared contributions of the next-to-next-to-leading order O(α 4 s ) radiative QCD corrections to the hadroproduction of heavy flavours. Our results, with the full mass dependence retained, are presented in a closed and very compact form, in dimensional regularization. (orig.)

  18. On the channel box for the fuel bundle of BWR

    International Nuclear Information System (INIS)

    Yokoyama, Hiroomi; Yamamoto, Takeo

    1976-01-01

    Channel boxes play the important roles of making coolant flow uniform and protecting fuel rods as the component of fuel assemblies for BWRs. About ten years ago, the domestic production of channel boxes was first investigated, and now, the original technology has been developed, and the channel boxes sufficiently satisfying the required quality can be produced. The actual experience by being charged in reactors has also been accumulated. At present, the supply capacity is almost sufficient to meet the domestic demand, and the future increase of demand can be dealt with promptly. The channel boxes are made of Zircaloy-4 plates which are favorable in view of neutron absorption, and are the boxes with 138 mm hollow square section, 2 mm thickness, and 4240 mm length. Two channels were welded together and made into a box. In order to eliminate the residual stress caused during the manufacture, high temperature heating with an electric furnace was adopted. The measurement of dimensions and the inspection of appearance of the channel boxes after irradiation proved that they were rather superior to imported ones. The production processes, the system for the quality guarantee, and the quality control in the Kobe Steel Ltd. are explained. The test and inspection are carried out at the time of accepting outside products, before starting the production, after the completion of longitudinal welding and after the completion of production. (Kako, I.)

  19. Sub-micrometer fluidic channel for measuring photon emitting entities

    Science.gov (United States)

    Stavis, Samuel M; Edel, Joshua B; Samiee, Kevan T; Craighead, Harold G

    2014-11-18

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  20. High aspect ratio channels in glass and porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Liang, H.D. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Nanoscience and Nanotechnology Initiative (NNI), National University of Singapore, Singapore 117411 (Singapore); Dang, Z.Y. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Wu, J.F. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583 (Singapore); Kan, J.A. van; Qureshi, S. [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Ynsa, M.D.; Torres-Costa, V. [Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Centro de Micro-Análisis de Materiales (CMAM), Universidad Autónoma de Madrid, Campus de Cantoblanco Edif. 22, Faraday 3, E-28049 Madrid (Spain); Maira, A. [Department of Applied Physics, Universidad Autónoma de Madrid, Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Venkatesan, T.V. [Nanoscience and Nanotechnology Initiative (NNI), National University of Singapore, Singapore 117411 (Singapore); Breese, M.B.H., E-mail: phymbhb@nus.edu.sg [Centre for Ion Beam Applications (CIBA), Department of Physics, National University of Singapore, Singapore 117542 (Singapore)

    2017-03-01

    We have developed a micromachining process to produce high-aspect-ratio channels and holes in glass and porous silicon. Our process utilizes MeV proton beam irradiation of silicon using direct writing with a focused beam, followed by electrochemical etching. To increase throughput we have also developed another process for large area ion irradiation based on a radiation-resistant gold surface mask, allowing many square inches to be patterned. We present a study of the achievable channel width, depth and period and sidewall verticality for a range of channels which can be over 100 μm deep or 100 nm wide with aspect ratios up to 80. This process overcomes the difficulty of machining glass on a micro- and nanometer scale which has limited many areas of applications in different fields such as microelectronics and microfluidics.

  1. Quantum dot conjugates in a sub-micrometer fluidic channel

    Science.gov (United States)

    Stavis, Samuel M.; Edel, Joshua B.; Samiee, Kevan T.; Craighead, Harold G.

    2010-04-13

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  2. Anisotropic transport of microalgae Chlorella vulgaris in microfluidic channel

    International Nuclear Information System (INIS)

    Ishak, Nur Izzati; Muniandy, S V; Periasamy, Vengadesh; Ng, Fong-Lee; Phang, Siew-Moi

    2017-01-01

    In this work, we study the regional dependence of transport behavior of microalgae Chlorella vulgaris inside microfluidic channel on applied fluid flow rate. The microalgae are treated as spherical naturally buoyant particles. Deviation from the normal diffusion or Brownian transport is characterized based on the scaling behavior of the mean square displacement (MSD) of the particle trajectories by resolving the displacements in the streamwise (flow) and perpendicular directions. The channel is divided into three different flow regions, namely center region of the channel and two near-wall boundaries and the particle motions are analyzed at different flow rates. We use the scaled Brownian motion to model the transitional characteristics in the scaling behavior of the MSDs. We find that there exist anisotropic anomalous transports in all the three flow regions with mixed sub-diffusive, normal and super-diffusive behavior in both longitudinal and transverse directions. (paper)

  3. Adaptive noise canceling of electrocardiogram artifacts in single channel electroencephalogram.

    Science.gov (United States)

    Cho, Sung Pil; Song, Mi Hye; Park, Young Cheol; Choi, Ho Seon; Lee, Kyoung Joung

    2007-01-01

    A new method for estimating and eliminating electrocardiogram (ECG) artifacts from single channel scalp electroencephalogram (EEG) is proposed. The proposed method consists of emphasis of QRS complex from EEG using least squares acceleration (LSA) filter, generation of synchronized pulse with R-peak and ECG artifacts estimation and elimination using adaptive filter. The performance of the proposed method was evaluated using simulated and real EEG recordings, we found that the ECG artifacts were successfully estimated and eliminated in comparison with the conventional multi-channel techniques, which are independent component analysis (ICA) and ensemble average (EA) method. From this we can conclude that the proposed method is useful for the detecting and eliminating the ECG artifacts from single channel EEG and simple to use for ambulatory/portable EEG monitoring system.

  4. Quantum dot conjugates in a sub-micrometer fluidic channel

    Science.gov (United States)

    Stavis, Samuel M [Ithaca, NY; Edel, Joshua B [Brookline, MA; Samiee, Kevan T [Ithaca, NY; Craighead, Harold G [Ithaca, NY

    2008-07-29

    A nanofluidic channel fabricated in fused silica with an approximately 500 nm square cross section was used to isolate, detect and identify individual quantum dot conjugates. The channel enables the rapid detection of every fluorescent entity in solution. A laser of selected wavelength was used to excite multiple species of quantum dots and organic molecules, and the emission spectra were resolved without significant signal rejection. Quantum dots were then conjugated with organic molecules and detected to demonstrate efficient multicolor detection. PCH was used to analyze coincident detection and to characterize the degree of binding. The use of a small fluidic channel to detect quantum dots as fluorescent labels was shown to be an efficient technique for multiplexed single molecule studies. Detection of single molecule binding events has a variety of applications including high throughput immunoassays.

  5. Making microbeams and nanobeams by channeling in microstructures and nanostructures

    Directory of Open Access Journals (Sweden)

    S. Bellucci

    2003-03-01

    Full Text Available A particle beam of very small cross section is useful in many accelerator applications including biological and medical ones. We show the capability of the channeling technique using a micron-sized structure on a surface of a single crystal, or using a nanotube, to produce a beam of a cross section down to one square micrometer (or nanometer. The channeled beam can be deflected and thus well separated in angle and space from the primary and scattered particles. Monte Carlo simulation is done to evaluate the characteristics of a channeled microbeam. Emittances down to 0.001 nm rad, and flux up to 10^{6}   μm^{2} per second, can be achieved for protons and ions.

  6. Influence of Route-R on wrought magnesium AZ61 alloy mechanical properties through equal channel angular pressing

    Directory of Open Access Journals (Sweden)

    Muralidhar Avvari

    2014-06-01

    Full Text Available A new fundamental route entitled ‘Route-R’ is introduced to refine the grains in the material through Equal Channel Angular Pressing (ECAP process. In route R, specimen is inverted to the original position in each ECAP pass. In the present work, AZ61 alloy is processed using ECAP process for three different fundamental routes mainly route A, route Bc, and route R. ECAP experiment is carried out on AZ61 alloy at lower temperature of 483 K up to two passes. Microstructural characterization is evaluated on unECAPed and ECAPed specimens for three routes. Average grain size of the alloy is to be reduced from 66 μm to 16 μm, 14.1 μm and 10 μm for route A routes Bc, and route R respectively. Vickers microhardness of the alloy is found to be 60 HV for as received material. This microhardness of the alloy is increased to 71 HV, 72 HV, and 74 HV for route A, route Bc, and route R respectively. Mechanical properties of the AZ61 alloy are observed to be route R is providing maximum YS, UTS, and percentage elongation than other route A and route Bc. Tensile fracture topography of the specimen is analyzed using three different routes for two passes.

  7. Spreading Sequence Design for Multiple Cell Synchronous DS-CDMA Systems under Total Weighted Squared Correlation Criterion

    Directory of Open Access Journals (Sweden)

    Cotae Paul

    2004-01-01

    Full Text Available An algorithm for designing spreading sequences for an overloaded multicellular synchronous DS-CDMA system on uplink is introduced. The criterion used to measure the optimality of the design is the total weighted square correlation (TWSC assuming the channel state information known perfectly at both transmitter and receiver. By using this algorithm it is possible to obtain orthogonal generalized WBE sequences sets for any processing gain. The bandwidth of initial generalized WBE signals of each cell is preserved in the extended signal space associated to multicellular system. Mathematical formalism is illustrated by selected numerical examples.

  8. MAGIC MOORE-PENROSE INVERSES AND PHILATELIC MAGIC SQUARES WITH SPECIAL EMPHASIS ON THE DANIELS–ZLOBEC MAGIC SQUARE

    Directory of Open Access Journals (Sweden)

    Ka Lok Chu

    2011-02-01

    Full Text Available We study singular magic matrices in which the numbers in the rows and columns and in the two main diagonals all add up to the same sum. Our interest focuses on such magic matrices for which the Moore–Penrose inverse is also magic. Special attention is given to the “Daniels–Zlobec magic square’’ introduced by the British magician and television performer Paul Daniels (b. 1938 and considered by Zlobec (2001; see also Murray (1989, pp. 30–32. We introduce the concept of a “philatelic magic square” as a square arrangement of images of postage stamps so that the associated nominal values form a magic square. Three philatelic magic squares with stamps especially chosen for Sanjo Zlobec are presented in celebration of his 70th birthday; most helpful in identifying these stamps was an Excel checklist by Männikkö (2009.

  9. Dual-goniometer system for channeling measurements

    International Nuclear Information System (INIS)

    Linden, M.; Hellborg, R.

    1986-03-01

    This paper describes a two-goniometer system for obtaining azimuthally averaged measurements in channeling experiments. The system consists of a tri-axial master goniometer and a bi-axial goniometer. Both goniometers are controlled by stepping motors. The alignment goniometer has a target holder, which permits the beam spot to be placed anywhere in a 6 x 6 mm 2 square on the target crystal without loosing the target orientation. The design, construction and operation of the goniometers as well as stepping motor control units and programs for computer control of the goniometers are described. Two control programs cover orientation of the target crystal and a number of other normal experimental conditions. (author)

  10. Moving least squares simulation of free surface flows

    DEFF Research Database (Denmark)

    Felter, C. L.; Walther, Jens Honore; Henriksen, Christian

    2014-01-01

    In this paper a Moving Least Squares method (MLS) for the simulation of 2D free surface flows is presented. The emphasis is on the governing equations, the boundary conditions, and the numerical implementation. The compressible viscous isothermal Navier–Stokes equations are taken as the starting ...

  11. Performance Evaluation of the Ordinary Least Square (OLS) and ...

    African Journals Online (AJOL)

    Nana Kwasi Peprah

    1Deparment of Geomatic Engineering, University of Mines and Technology, ... precise, accurate and can be used to execute any engineering works due to ..... and Ordinary Least Squares Methods”, Journal of Geomatics and Planning, Vol ... Technology”, Unpublished BSc Project Report, University of Mines and Technology ...

  12. African Journal of Science and Technology (AJST) NON-SQUARE ...

    African Journals Online (AJOL)

    opiyo

    ABSTRACT: This paper presents calculations demonstrating that non-square quantum well growth. (well shaping) can result in reduced threshold current for tensilely strained quantum well bipolar diode lasers operating at 1.52µm m. Calculations of subband structure, optical matrix elements and laser gain are performed for ...

  13. The Massacre in Tiananmen Square: An Eye Witness Account.

    Science.gov (United States)

    Wolken, Lawrence C.

    1989-01-01

    Recounts personal observations of a former resident of the People's Republic of China during the events of the summer of 1989. Notes changes including a new sense of purpose and a spirit of openness, as well as improvement in the standard of living. Considers the impact of the tragic incident in Tiananmen Square on these improvements in Chinese…

  14. Tiananmen Square and China--One Year Later.

    Science.gov (United States)

    Doyle, Deborah

    1991-01-01

    Reports an individual's observations during a trip to China. Argues that the U.S. government and students must learn to understand and appreciate China because of its large population, market potential, and position among major world powers. Discusses personal impressions, the protesters at Tiananmen Square and elsewhere, and reactions to…

  15. Analysis of Nonlinear Dynamics by Square Matrix Method

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Li Hua [Brookhaven National Lab. (BNL), Upton, NY (United States). Energy and Photon Sciences Directorate. National Synchrotron Light Source II

    2016-07-25

    The nonlinear dynamics of a system with periodic structure can be analyzed using a square matrix. In this paper, we show that because the special property of the square matrix constructed for nonlinear dynamics, we can reduce the dimension of the matrix from the original large number for high order calculation to low dimension in the first step of the analysis. Then a stable Jordan decomposition is obtained with much lower dimension. The transformation to Jordan form provides an excellent action-angle approximation to the solution of the nonlinear dynamics, in good agreement with trajectories and tune obtained from tracking. And more importantly, the deviation from constancy of the new action-angle variable provides a measure of the stability of the phase space trajectories and their tunes. Thus the square matrix provides a novel method to optimize the nonlinear dynamic system. The method is illustrated by many examples of comparison between theory and numerical simulation. Finally, in particular, we show that the square matrix method can be used for optimization to reduce the nonlinearity of a system.

  16. Counting Your Way to the Sum of Squares Formula

    Indian Academy of Sciences (India)

    IAS Admin

    This gives us a brand new formula for the sum of the squares of the first n positive integers! A small tweak gives us a second formula, for free! For, we have the following identity for the binomial coeffi- cients which comes from the well known recursive rela- tion which the binomial coefficients satisfy: (n + 1. 3 )+ ( n + 1. 2 )= (.

  17. Latin-square three-dimensional gage master

    Science.gov (United States)

    Jones, L.

    1981-05-12

    A gage master for coordinate measuring machines has an nxn array of objects distributed in the Z coordinate utilizing the concept of a Latin square experimental design. Using analysis of variance techniques, the invention may be used to identify sources of error in machine geometry and quantify machine accuracy.

  18. Non linear-least-squares fitting for pixe spectra

    International Nuclear Information System (INIS)

    Benamar, M.A.; Tchantchane, A.; Benouali, N.; Azbouche, A.; Tobbeche, S.

    1992-10-01

    An interactive computer program for the analysis of Pixe spectra is described. The fitting procedure consists of computing a function which approximates the experimental data. A nonlinear least-squares fitting is used to determine the parameters of the fit. The program takes into account the low energy tail and the escape peaks

  19. Noninteracting Fermi gas in a square-well potential.

    Science.gov (United States)

    Nash, C. E.

    1971-01-01

    The problem of a noninteracting Fermi gas in a finite square-well potential is solved analytically in the limit that the well becomes infinitely wide. The errors of previous authors using this model as a first approximation to the problem of a simple metal with surfaces are pointed out.

  20. Plane-wave Least-squares Reverse Time Migration

    KAUST Repository

    Dai, Wei

    2012-11-04

    Least-squares reverse time migration is formulated with a new parameterization, where the migration image of each shot is updated separately and a prestack image is produced with common image gathers. The advantage is that it can offer stable convergence for least-squares migration even when the migration velocity is not completely accurate. To significantly reduce computation cost, linear phase shift encoding is applied to hundreds of shot gathers to produce dozens of planes waves. A regularization term which penalizes the image difference between nearby angles are used to keep the prestack image consistent through all the angles. Numerical tests on a marine dataset is performed to illustrate the advantages of least-squares reverse time migration in the plane-wave domain. Through iterations of least-squares migration, the migration artifacts are reduced and the image resolution is improved. Empirical results suggest that the LSRTM in plane wave domain is an efficient method to improve the image quality and produce common image gathers.

  1. Multivariate calibration with least-squares support vector machines.

    NARCIS (Netherlands)

    Thissen, U.M.J.; Ustun, B.; Melssen, W.J.; Buydens, L.M.C.

    2004-01-01

    This paper proposes the use of least-squares support vector machines (LS-SVMs) as a relatively new nonlinear multivariate calibration method, capable of dealing with ill-posed problems. LS-SVMs are an extension of "traditional" SVMs that have been introduced recently in the field of chemistry and

  2. Steel Housing - The Reinvention of the Square Wheel?

    NARCIS (Netherlands)

    Willems, M.H.P.M.

    2002-01-01

    Steel housing has some remarkable resemblance with a square wheel. Both combine a simple concept, uncommon appearance and lack of appreciation. The title furthermore refers to the repeated stubborn efforts over the last decennia to develop prefabricated steel-based housing systems. Steel has

  3. Table of nuclear root mean square charge radii. Summary

    International Nuclear Information System (INIS)

    Paviotti-Corcuera, R.; McLaughlin, P.K.

    1999-01-01

    This document describes a table of nuclear root-mean-square (rms) charge radii evaluated by two different procedures. The data are available from the IAEA Nuclear Data Section via INTERNET or on PC diskettes upon request. This document supersedes the previous IAEA-NDS-163, 1990, 'Nuclear Charge Radii'. (author)

  4. El nuevo Madison Square Garden – (EE.UU.

    Directory of Open Access Journals (Sweden)

    Luckman, Ch.

    1971-05-01

    Full Text Available The Madison Square Garden Sports and Amusements Center comprises the following. 1. A circular building, 129.54 m in diameter and 45.72 m high, which houses the New Madison Square Garden and many other facilities. The arena sits 20.250 spectators, who can watch hockey, basketball, cycling, boxing, circus shows, ice skating, special displays, variety shows, meetings and other kinds of performance. 2. An office block on Seventh Avenue, with a useful floor area for office use amounting to 111,500 m2 and a further 4,800 m2 of floor area on the first two floors for commercial and banking activities.Forman parte del Centro Deportivo y de Atracciones Madison Square Garden: 1 Un edificio circular, de 129,54 m de diámetro y 45,72 m de altura, que aloja el Nuevo Madison Square Garden y otras muchas instalaciones. Tiene capacidad para 20.250 asientos, y en él se pueden celebrar espectáculos de: hockey, baloncesto, ciclismo, boxeo, circo, patinaje sobre hielo, acontecimientos especiales, variedades, asambleas y otros deportes de masas, etc. 2 Un edificio de oficinas que se alza contiguo a la Séptima Avenida, con una superficie útil de 111.500 m2 destinada a oficinas, y otra de 4.800 m2, en las plantas primera y segunda, dedicada a actividades comerciales y bancarias.

  5. Thermal performance in circular tube fitted with coiled square wires

    International Nuclear Information System (INIS)

    Promvonge, Pongjet

    2008-01-01

    The effects of wires with square cross section forming a coil used as a turbulator on the heat transfer and turbulent flow friction characteristics in a uniform heat flux, circular tube are experimentally investigated in the present work. The experiments are performed for flows with Reynolds numbers ranging from 5000 to 25,000. Two different spring coiled wire pitches are introduced. The results are also compared with those obtained from using a typical coiled circular wire, apart from the smooth tube. The experimental results reveal that the use of coiled square wire turbulators leads to a considerable increase in heat transfer and friction loss over those of a smooth wall tube. The Nusselt number increases with the rise of Reynolds number and the reduction of pitch for both circular and square wire coils. The coiled square wire provides higher heat transfer than the circular one under the same conditions. Also, performance evaluation criteria to assess the real benefits in using both coil wires of the enhanced tube are determined

  6. The square of opposition a cornerstone of thought

    CERN Document Server

    Basti, Gianfranco

    2017-01-01

    This is a collection of new investigations and discoveries on the theory of opposition (square, hexagon, octagon, polyhedra of opposition) by the best specialists from all over the world. The papers range from historical considerations to new mathematical developments of the theory of opposition including applications to theology, theory of argumentation and metalogic.

  7. Mean square exponential stability of stochastic delayed Hopfield neural networks

    International Nuclear Information System (INIS)

    Wan Li; Sun Jianhua

    2005-01-01

    Stochastic effects to the stability property of Hopfield neural networks (HNN) with discrete and continuously distributed delay are considered. By using the method of variation parameter, inequality technique and stochastic analysis, the sufficient conditions to guarantee the mean square exponential stability of an equilibrium solution are given. Two examples are also given to demonstrate our results

  8. Madhava, Gregory, Leibnitz, and Sums of Two Squares

    Indian Academy of Sciences (India)

    IAS Admin

    Keywords. Gregory–Leibnitz series, lattice points, sums of two squares,. Gauss circle problem. Shailesh Shirali heads the. Community Math Centre in Rishi Valley School and works in the field of teacher education. He is the author of many books and articles in mathemat- ics, written for interested students in the age range.

  9. Wave-equation Q tomography and least-squares migration

    KAUST Repository

    Dutta, Gaurav

    2016-01-01

    optimization method that inverts for the subsurface Q distribution by minimizing a skeletonized misfit function ε. Here, ε is the sum of the squared differences between the observed and the predicted peak/centroid-frequency shifts of the early-arrivals. Through

  10. Preconditioned Iterative Methods for Solving Weighted Linear Least Squares Problems

    Czech Academy of Sciences Publication Activity Database

    Bru, R.; Marín, J.; Mas, J.; Tůma, Miroslav

    2014-01-01

    Roč. 36, č. 4 (2014), A2002-A2022 ISSN 1064-8275 Institutional support: RVO:67985807 Keywords : preconditioned iterative methods * incomplete decompositions * approximate inverses * linear least squares Subject RIV: BA - General Mathematics Impact factor: 1.854, year: 2014

  11. Changing public space. The recent redevelopment of Dutch city squares

    NARCIS (Netherlands)

    van Melik, R.G.

    2008-01-01

    Public spaces in Dutch city centres are increasingly subject to facelifts. The car parking that dominated city squares until the 1980s has been removed and replaced by modern street furniture, city stages, and an abundance of sidewalk caf鳮 At the same time, public spaces are more controlled by

  12. Double asymptotics for the chi-square statistic.

    Science.gov (United States)

    Rempała, Grzegorz A; Wesołowski, Jacek

    2016-12-01

    Consider distributional limit of the Pearson chi-square statistic when the number of classes m n increases with the sample size n and [Formula: see text]. Under mild moment conditions, the limit is Gaussian for λ = ∞, Poisson for finite λ > 0, and degenerate for λ = 0.

  13. Least-mean-square spatial filter for IR sensors.

    Science.gov (United States)

    Takken, E H; Friedman, D; Milton, A F; Nitzberg, R

    1979-12-15

    A new least-mean-square filter is defined for signal-detection problems. The technique is proposed for scanning IR surveillance systems operating in poorly characterized but primarily low-frequency clutter interference. Near-optimal detection of point-source targets is predicted both for continuous-time and sampled-data systems.

  14. Some Results on Mean Square Error for Factor Score Prediction

    Science.gov (United States)

    Krijnen, Wim P.

    2006-01-01

    For the confirmatory factor model a series of inequalities is given with respect to the mean square error (MSE) of three main factor score predictors. The eigenvalues of these MSE matrices are a monotonic function of the eigenvalues of the matrix gamma[subscript rho] = theta[superscript 1/2] lambda[subscript rho] 'psi[subscript rho] [superscript…

  15. Restoration and the City: The Role of Public Urban Squares

    Directory of Open Access Journals (Sweden)

    César San Juan

    2017-12-01

    Full Text Available Over recent decades, the study of psychological restoration has attracted a considerable amount of interest within and without the boundaries of environmental psychology, with most of the work focused on analyzing restoration in natural contexts. However, little attention has been paid to the (possible restorative potential of urban settings, as they have usually been expected not to be restorative and to present some elements that might imply negative health outcomes in the short and long term. In this field study, our aim was to evaluate restoration in urban squares. To this end, we measured participants' attentional and affective states both before and after spending half an hour in an urban square. A sample of 46 subjects contemplated and walked through one of the two selected squares that differed in restorative potential (PRS. Analyses revealed a statistically significant increase in cognitive performance and a decrease in negative affect in both squares. They also showed that participants reported greater stress recovery rates in one of the settings. These results support the idea that cities can be potentially restorative and justify the relevance of a research area focused on the urban designs, which may offer psychological benefits to urban citizens.

  16. On squaring the primary constraints in a generalized Hamiltonian dynamics

    International Nuclear Information System (INIS)

    Nesterenko, V.V.

    1993-01-01

    Consideration of the model of the relativistic particle with curvature and torsion in the three-dimensional space-time shows that the squaring of the primary constraints entails a wrong result. The complete set of the Hamiltonian constraints arising here corresponds to another model with an action similar but not identical with the initial action. 16 refs

  17. Some results on square-free colorings of graphs

    DEFF Research Database (Denmark)

    Barat, Janos

    2004-01-01

    on the vertices or edges of a path. Conversely one can form sequences from a vertex or edge coloring of a graph in different ways. Thus there are several possibilities to generalize the square-free concept to graphs. Following Alon, Grytczuk, Haluszczak, Riordan and Bresar, Klavzar we study several so called...... square-free graph parameters, and answer some questions they posed. The main result is that the class of k-trees has bounded square-free vertex coloring parameter. Thus we can color the vertices of a k-tree using O(c^k) colors if c>6 such that the color sequence on any path is square......-free. It is conjectured that a similar phenomenon holds for planar graphs, so a finite number of colors are enough. We support this conjecture by showing that this number is at most 12 for outerplanar graphs. On the other hand we prove that some outerplanar graphs require at least 7 colors. Using this latter we construct...

  18. Quantum communication under channel uncertainty

    International Nuclear Information System (INIS)

    Noetzel, Janis Christian Gregor

    2012-01-01

    This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

  19. VAX CAMAC channel

    International Nuclear Information System (INIS)

    Nelson, D.J.; Breidenbach, M.; Granieri, C.D.; Grund, J.E.; Patrick, J.F.; Weaver, L.J.

    1980-10-01

    A new generation CAMAC System has been developed for the Mark II Detector at SLAC's PEP storage ring. This flexible system can efficiently transfer data between a host computer and a very large set of CAMAC data acquisition and control modules. A bipolar microprocessor operates as a Channel interface by supervising the CAMAC system and minimizing the host computer's work. This programmable channel couples the host to a set of System Crates; each System Crate houses Branch Drivers that can directly control a set of crates or communicate over differential parallel highways to Branch Receivers for control of distant crates. A coherent software package integrates the high level programs, system driver level programs, and microcode control of the system

  20. Geysering in boiling channels

    Energy Technology Data Exchange (ETDEWEB)

    Aritomi, Masanori; Takemoto, Takatoshi [Tokyo Institute of Technology, Tokyo (Japan); Chiang, Jing-Hsien [Japan NUS Corp. Ltd., Toyko (Japan)] [and others

    1995-09-01

    A concept of natural circulation BWRs such as the SBWR has been proposed and seems to be promising in that the primary cooling system can be simplified. The authors have been investigating thermo-hydraulic instabilities which may appear during the start-up in natural circulation BWRs. In our previous works, geysering was investigated in parallel boiling channels for both natural and forced circulations, and its driving mechanism and the effect of system pressure on geysering occurrence were made clear. In this paper, geysering is investigated in a vertical column and a U-shaped vertical column heated in the lower parts. It is clarified from the results that the occurrence mechanism of geysering and the dependence of system pressure on geysering occurrence coincide between parallel boiling channels in circulation systems and vertical columns in non-circulation systems.

  1. Coolant channel module CCM

    International Nuclear Information System (INIS)

    Hoeld, Alois

    2007-01-01

    A complete and detailed description of the theoretical background of an '(1D) thermal-hydraulic drift-flux based mixture-fluid' coolant channel model and its resulting module CCM will be presented. The objective of this module is to simulate as universally as possible the steady state and transient behaviour of the key characteristic parameters of a single- or two-phase fluid flowing within any type of heated or non-heated coolant channel. Due to the possibility that different flow regimes can appear along any channel, such a 'basic (BC)' 1D channel is assumed to be subdivided into a number of corresponding sub-channels (SC-s). Each SC can belong to only two types of flow regime, an SC with just a single-phase fluid, containing exclusively either sub-cooled water or superheated steam, or an SC with a two-phase mixture flow. After an appropriate nodalisation of such a BC (and therefore also its SC-s) a 'modified finite volume method' has been applied for the spatial discretisation of the partial differential equations (PDE-s) which represent the basic conservation equations of thermal-hydraulics. Special attention had to be given to the possibility of variable SC entrance or outlet positions (which describe boiling boundaries or mixture levels) and thus the fact that an SC can even disappear or be created anew. The procedure yields for each SC type (and thus the entire BC), a set of non-linear ordinary 1st order differential equations (ODE-s). To link the resulting mean nodal with the nodal boundary function values, both of which are present in the discretised differential equations, a special quadratic polygon approximation procedure (PAX) had to be constructed. Together with the very thoroughly tested packages for drift-flux, heat transfer and single- and two-phase friction factors this procedure represents the central part of the here presented 'Separate-Region' approach, a theoretical model which provides the basis to the very effective working code package CCM

  2. Tourism distribution channels

    OpenAIRE

    Camilleri, Mark Anthony

    2017-01-01

    The distribution channels link the customers with the businesses. For many years, the tourism businesses may have distributed their products and services through intermediaries. However, the latest advances in technology have brought significant changes in this regard. More individuals and corporate customers are increasingly benefiting of ubiquitous technologies, including digital media. The development of mobile devices and their applications, are offering a wide range of possibilities to t...

  3. Athermal channeled spectropolarimeter

    Science.gov (United States)

    Jones, Julia Craven

    2015-12-08

    A temperature insensitive (athermal) channeled spectropolarimeter (CSP) is described. The athermal CSP includes a crystal retarder formed of a biaxial crystal. The crystal retarder has three crystal axes, wherein each axis has its own distinct index of refraction. The axes are oriented in a particular manner, causing an amplitude modulating carrier frequency induced by the crystal retarder to be thermally invariant. Accordingly, a calibration beam technique can be used over a relatively wide range of ambient temperatures, with a common calibration data set.

  4. Nuclear reactor coolant channels

    International Nuclear Information System (INIS)

    Macbeth, R.V.

    1978-01-01

    A nuclear reactor coolant channel is described that is suitable for sub-cooled reactors as in pressurised water reactors as well as for bulk boiling, as in boiling water reactors and steam generating nuclear reactors. The arrangement aims to improve heat transfer between the fuel elements and the coolant. Full constructional details are given. See also other similar patents by the author. (U.K.)

  5. The M2 Channel

    DEFF Research Database (Denmark)

    Santner, Paul

    Drug resistance of Influenza A against antivirals is an increasing problem. No effective Influenza A drugs targeting the crucial viral protein, the proton transporter M2 are available anymore due to widespread resistance. Thanks to research efforts elucidating M2 protein structure, function and i...... resistance escape routes from drug inhibition. We thereby were hopefully able to provide a platform for the large-scale evaluation of M2 channel activity, inhibitors and resistance....

  6. Aquaglyceroporins: generalized metalloid channels

    Science.gov (United States)

    Mukhopadhyay, Rita; Bhattacharjee, Hiranmoy; Rosen, Barry P.

    2014-01-01

    Background: Aquaporins (AQPs), members of a superfamily of transmembrane channel proteins, are ubiquitous in all domains of life. They fall into a number of branches that can be functionally categorized into two major sub-groups: i) orthodox aquaporins, which are water-specific channels, and ii) aquaglyceroporins, which allow the transport of water, non-polar solutes, such as urea or glycerol, the reactive oxygen species hydrogen peroxide, and gases such as ammonia, carbon dioxide and nitric oxide and, as described in this review, metalloids. Scope of Review: This review summarizes the key findings that AQP channels conduct bidirectional movement of metalloids into and out of cells. Major Conclusions: As(OH)3 and Sb(OH)3 behave as inorganic molecular mimics of glycerol, a property that allows their passage through AQP channels. Plant AQPs also allow the passage of boron and silicon as their hydroxyacids, boric acid (B(OH)3) and orthosilicic acid (Si(OH)4), respectively. Genetic analysis suggests that germanic acid (GeO2) is also a substrate. While As(III), Sb(III) and Ge(IV) are toxic metalloids, borate (B(III)) and silicate (Si(IV)) are essential elements in higher plants. General Significance: The uptake of environmental metalloids by aquaporins provides an understanding of (i) how toxic elements such as arsenic enter the food chain; (ii) the delivery of arsenic and antimony containing drugs in the treatment of certain forms of leukemia and chemotherapy of diseases caused by pathogenic protozoa; and (iii) the possibility that food plants such as rice could be made safer by genetically modifying them to exclude arsenic while still accumulating boron and silicon. PMID:24291688

  7. Matching Dyadic Distributions to Channels

    OpenAIRE

    Böcherer, Georg; Mathar, Rudolf

    2010-01-01

    Many communication channels with discrete input have non-uniform capacity achieving probability mass functions (PMF). By parsing a stream of independent and equiprobable bits according to a full prefix-free code, a modu-lator can generate dyadic PMFs at the channel input. In this work, we show that for discrete memoryless channels and for memoryless discrete noiseless channels, searching for good dyadic input PMFs is equivalent to minimizing the Kullback-Leibler distance between a dyadic PMF ...

  8. Radar channel balancing with commutation

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.

  9. Microstructural information from channeling measurements

    International Nuclear Information System (INIS)

    Quere, Y.

    1984-09-01

    Channeling is sensitive to nearly all structural changes in solids. One briefly recalls how particles are dechanneled by lattice defects and describes the main applications of channeling to materials science: detection of radiation damage, location of impurity atoms, precipitations in alloys... Channeling being a phenomenon characteristic of perfect crystals, any type of lattice imperfection (phonons, crystal defects, precipitation etc.) is expected to produce dechanneling. Consequently channeling and its opposite, dechanneling, have both been used to study structure and structural changes of materials

  10. Ion channeling revisited

    Energy Technology Data Exchange (ETDEWEB)

    Doyle, Barney Lee [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Corona, Aldo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Nguyen, Anh [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-09-01

    A MS Excel program has been written that calculates accidental, or unintentional, ion channeling in cubic bcc, fcc and diamond lattice crystals or polycrystalline materials. This becomes an important issue when simulating the creation by energetic neutrons of point displacement damage and extended defects using beams of ions. All of the tables and graphs in the three Ion Beam Analysis Handbooks that previously had to be manually looked up and read from were programed into Excel in handy lookup tables, or parameterized, for the case of the graphs, using rather simple exponential functions with different powers of the argument. The program then offers an extremely convenient way to calculate axial and planar half-angles and minimum yield or dechanneling probabilities, effects on half-angles of amorphous overlayers, accidental channeling probabilities for randomly oriented crystals or crystallites, and finally a way to automatically generate stereographic projections of axial and planar channeling half-angles. The program can generate these projections and calculate these probabilities for axes and [hkl] planes up to (555).

  11. The alpha channeling effect

    Science.gov (United States)

    Fisch, N. J.

    2015-12-01

    Alpha particles born through fusion reactions in a tokamak reactor tend to slow down on electrons, but that could take up to hundreds of milliseconds. Before that happens, the energy in these alpha particles can destabilize on collisionless timescales toroidal Alfven modes and other waves, in a way deleterious to energy confinement. However, it has been speculated that this energy might be instead be channeled into useful energy, so as to heat fuel ions or to drive current. Such a channeling needs to be catalyzed by waves Waves can produce diffusion in energy of the alpha particles in a way that is strictly coupled to diffusion in space. If these diffusion paths in energy-position space point from high energy in the center to low energy on the periphery, then alpha particles will be cooled while forced to the periphery. The energy from the alpha particles is absorbed by the wave. The amplified wave can then heat ions or drive current. This process or paradigm for extracting alpha particle energy collisionlessly has been called alpha channeling. While the effect is speculative, the upside potential for economical fusion is immense. The paradigm also operates more generally in other contexts of magnetically confined plasma.

  12. TRP channels in kidney disease.

    NARCIS (Netherlands)

    Hsu, Y.J.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2007-01-01

    Mammalian TRP channel proteins form six-transmembrane cation-permeable channels that may be grouped into six subfamilies on the basis of amino acid sequence homology (TRPC, TRPV, TRPM, TRPA, TRPP, and TRPML). Recent studies of TRP channels indicate that they are involved in numerous fundamental cell

  13. Parallel inter channel interaction mechanisms

    International Nuclear Information System (INIS)

    Jovic, V.; Afgan, N.; Jovic, L.

    1995-01-01

    Parallel channels interactions are examined. For experimental researches of nonstationary regimes flow in three parallel vertical channels results of phenomenon analysis and mechanisms of parallel channel interaction for adiabatic condition of one-phase fluid and two-phase mixture flow are shown. (author)

  14. Modeling of MHD natural convection in a square enclosure having an adiabatic square shaped body using Lattice Boltzmann Method

    Directory of Open Access Journals (Sweden)

    Ahmed Kadhim Hussein

    2016-03-01

    Full Text Available A steady laminar two-dimensional magneto-hydrodynamics (MHD natural convection flow in a square enclosure filled with an electrically conducting fluid is numerically investigated using Lattice Boltzmann Method (LBM. The left and right vertical sidewalls of the square enclosure are maintained at hot and cold temperatures respectively. The horizontal top and bottom walls are considered thermally insulated. An adiabatic square shaped body is located in the center of a square enclosure and an external magnetic field is applied parallel to the horizontal x-axis. In the present work, the following parametric ranges of the non-dimensional groups are utilized: Hartmann number is varied as 0 ⩽ Ha ⩽ 50, Rayleigh number is varied as 103 ⩽ Ra ⩽ 105, Prandtl number is varied 0.05 ⩽ Pr ⩽ 5. It is found that the Hartmann number, Rayleigh number, and Prandtl number have an important role on the flow and thermal characteristics. It is found that when the Hartmann number increases the average Nusselt number decreases. The results also explain that the effect of magnetic field on flow field increases by increasing Prandtl number. However, the Prandtl number effect on the average Nusselt number with a magnetic field is less than the case without a magnetic field. Comparisons with previously published numerical works are performed and good agreements between the results are observed.

  15. Penalized linear regression for discrete ill-posed problems: A hybrid least-squares and mean-squared error approach

    KAUST Repository

    Suliman, Mohamed Abdalla Elhag; Ballal, Tarig; Kammoun, Abla; Al-Naffouri, Tareq Y.

    2016-01-01

    This paper proposes a new approach to find the regularization parameter for linear least-squares discrete ill-posed problems. In the proposed approach, an artificial perturbation matrix with a bounded norm is forced into the discrete ill-posed model

  16. Effect of longitudinal and transverse vibrations of an upstream square cylinder on vortex shedding behind two inline square cylinders

    International Nuclear Information System (INIS)

    Patil, Pratish P; Tiwari, Shaligram

    2009-01-01

    The characteristics of unsteady wakes behind a stationary square cylinder and another upstream vibrating square cylinder have been investigated numerically with the help of a developed computational code. The effect of longitudinal as well as transverse vibrations of the upstream cylinder is studied on the coupled wake between the two cylinders, which is found to control the vortex shedding behavior behind the downstream stationary cylinder. Computations are carried out for a fixed value of Reynolds number (Re = 200) and three different values of excitation frequencies of the upstream cylinder, namely less than, equal to and greater than the natural frequency of vortex shedding corresponding to flow past a stationary square cylinder. The vortex shedding characteristics of the unsteady wakes behind the vibrating and stationary cylinders are found to differ significantly for longitudinal and transverse modes of vibration of the upstream cylinder. The wake of the downstream stationary cylinder is found to depict a synchronization behavior with the upstream cylinder vibration. The spacing between the two cylinders has been identified to be the key parameter influencing the synchronization phenomenon. The effect of cylinder spacing on the wake synchronization and the hydrodynamic forces has been examined. In addition, a comparison of the drag forces for flow past transversely vibrating square and circular cylinders for similar amplitudes and frequencies of cylinder vibration has been presented while employing the tested computational code.

  17. Voltage-Gated Calcium Channels

    Science.gov (United States)

    Zamponi, Gerald Werner

    Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

  18. Pilot-based parametric channel estimation algorithm for DCO-OFDM-based visual light communications

    Science.gov (United States)

    Qian, Xuewen; Deng, Honggui; He, Hailang

    2017-10-01

    Due to wide modulation bandwidth in optical communication, multipath channels may be non-sparse and deteriorate communication performance heavily. Traditional compressive sensing-based channel estimation algorithm cannot be employed in this kind of situation. In this paper, we propose a practical parametric channel estimation algorithm for orthogonal frequency division multiplexing (OFDM)-based visual light communication (VLC) systems based on modified zero correlation code (ZCC) pair that has the impulse-like correlation property. Simulation results show that the proposed algorithm achieves better performances than existing least squares (LS)-based algorithm in both bit error ratio (BER) and frequency response estimation.

  19. Iterative Sparse Channel Estimation and Decoding for Underwater MIMO-OFDM

    Directory of Open Access Journals (Sweden)

    Berger ChristianR

    2010-01-01

    Full Text Available We propose a block-by-block iterative receiver for underwater MIMO-OFDM that couples channel estimation with multiple-input multiple-output (MIMO detection and low-density parity-check (LDPC channel decoding. In particular, the channel estimator is based on a compressive sensing technique to exploit the channel sparsity, the MIMO detector consists of a hybrid use of successive interference cancellation and soft minimum mean-square error (MMSE equalization, and channel coding uses nonbinary LDPC codes. Various feedback strategies from the channel decoder to the channel estimator are studied, including full feedback of hard or soft symbol decisions, as well as their threshold-controlled versions. We study the receiver performance using numerical simulation and experimental data collected from the RACE08 and SPACE08 experiments. We find that iterative receiver processing including sparse channel estimation leads to impressive performance gains. These gains are more pronounced when the number of available pilots to estimate the channel is decreased, for example, when a fixed number of pilots is split between an increasing number of parallel data streams in MIMO transmission. For the various feedback strategies for iterative channel estimation, we observe that soft decision feedback slightly outperforms hard decision feedback.

  20. A New Maximum-Likelihood Change Estimator for Two-Pass SAR Coherent Change Detection.

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, Daniel E.; Yocky, David A.; Jakowatz, Charles V,

    2014-09-01

    In this paper, we derive a new optimal change metric to be used in synthetic aperture RADAR (SAR) coherent change detection (CCD). Previous CCD methods tend to produce false alarm states (showing change when there is none) in areas of the image that have a low clutter-to-noise power ratio (CNR). The new estimator does not suffer from this shortcoming. It is a surprisingly simple expression, easy to implement, and is optimal in the maximum-likelihood (ML) sense. The estimator produces very impressive results on the CCD collects that we have tested.

  1. A Two-Pass Exact Algorithm for Selection on Parallel Disk Systems.

    Science.gov (United States)

    Mi, Tian; Rajasekaran, Sanguthevar

    2013-07-01

    Numerous OLAP queries process selection operations of "top N", median, "top 5%", in data warehousing applications. Selection is a well-studied problem that has numerous applications in the management of data and databases since, typically, any complex data query can be reduced to a series of basic operations such as sorting and selection. The parallel selection has also become an important fundamental operation, especially after parallel databases were introduced. In this paper, we present a deterministic algorithm Recursive Sampling Selection (RSS) to solve the exact out-of-core selection problem, which we show needs no more than (2 + ε ) passes ( ε being a very small fraction). We have compared our RSS algorithm with two other algorithms in the literature, namely, the Deterministic Sampling Selection and QuickSelect on the Parallel Disks Systems. Our analysis shows that DSS is a (2 + ε )-pass algorithm when the total number of input elements N is a polynomial in the memory size M (i.e., N = M c for some constant c ). While, our proposed algorithm RSS runs in (2 + ε ) passes without any assumptions. Experimental results indicate that both RSS and DSS outperform QuickSelect on the Parallel Disks Systems. Especially, the proposed algorithm RSS is more scalable and robust to handle big data when the input size is far greater than the core memory size, including the case of N ≫ M c .

  2. Steady squares and hexagons on a subcritical ramp

    International Nuclear Information System (INIS)

    Hoyle, R.B.

    1995-01-01

    Steady squares and hexagons on a subcritical ramp are studied, both analytically and numerically, within the framework of the lowest-order amplitude equations. On the subcritical ramp, the external stress or control parameter varies continuously in space from subcritical to supercritical values. At the subcritical end of the ramp, pattern formation is suppressed, and patterns fade away into the conduction solution. It is shown that three-dimensional patterns may change shape on a subcritical ramp. A square pattern becomes a pattern of rolls as it fades, with the roll axes aligned in the direction orthogonal to that in which the control parameter varies. Hexagons in systems with horizontal midplane symmetry become a pattern of rectangles before reaching the conduction solution. There is a suggestion that hexagons in systems which lack this symmetry might fade away through a roll pattern. Numerical simulations are used to illustrate these phenomena

  3. Linearized least-square imaging of internally scattered data

    KAUST Repository

    Aldawood, Ali; Hoteit, Ibrahim; Turkiyyah, George M.; Zuberi, M. A H; Alkhalifah, Tariq Ali

    2014-01-01

    Internal multiples deteriorate the quality of the migrated image obtained conventionally by imaging single scattering energy. However, imaging internal multiples properly has the potential to enhance the migrated image because they illuminate zones in the subsurface that are poorly illuminated by single-scattering energy such as nearly vertical faults. Standard migration of these multiples provide subsurface reflectivity distributions with low spatial resolution and migration artifacts due to the limited recording aperture, coarse sources and receivers sampling, and the band-limited nature of the source wavelet. Hence, we apply a linearized least-square inversion scheme to mitigate the effect of the migration artifacts, enhance the spatial resolution, and provide more accurate amplitude information when imaging internal multiples. Application to synthetic data demonstrated the effectiveness of the proposed inversion in imaging a reflector that is poorly illuminated by single-scattering energy. The least-square inversion of doublescattered data helped delineate that reflector with minimal acquisition fingerprint.

  4. An information geometric approach to least squares minimization

    Science.gov (United States)

    Transtrum, Mark; Machta, Benjamin; Sethna, James

    2009-03-01

    Parameter estimation by nonlinear least squares minimization is a ubiquitous problem that has an elegant geometric interpretation: all possible parameter values induce a manifold embedded within the space of data. The minimization problem is then to find the point on the manifold closest to the origin. The standard algorithm for minimizing sums of squares, the Levenberg-Marquardt algorithm, also has geometric meaning. When the standard algorithm fails to efficiently find accurate fits to the data, geometric considerations suggest improvements. Problems involving large numbers of parameters, such as often arise in biological contexts, are notoriously difficult. We suggest an algorithm based on geodesic motion that may offer improvements over the standard algorithm for a certain class of problems.

  5. Unweighted least squares phase unwrapping by means of multigrid techniques

    Science.gov (United States)

    Pritt, Mark D.

    1995-11-01

    We present a multigrid algorithm for unweighted least squares phase unwrapping. This algorithm applies Gauss-Seidel relaxation schemes to solve the Poisson equation on smaller, coarser grids and transfers the intermediate results to the finer grids. This approach forms the basis of our multigrid algorithm for weighted least squares phase unwrapping, which is described in a separate paper. The key idea of our multigrid approach is to maintain the partial derivatives of the phase data in separate arrays and to correct these derivatives at the boundaries of the coarser grids. This maintains the boundary conditions necessary for rapid convergence to the correct solution. Although the multigrid algorithm is an iterative algorithm, we demonstrate that it is nearly as fast as the direct Fourier-based method. We also describe how to parallelize the algorithm for execution on a distributed-memory parallel processor computer or a network-cluster of workstations.

  6. Estimating Frequency by Interpolation Using Least Squares Support Vector Regression

    Directory of Open Access Journals (Sweden)

    Changwei Ma

    2015-01-01

    Full Text Available Discrete Fourier transform- (DFT- based maximum likelihood (ML algorithm is an important part of single sinusoid frequency estimation. As signal to noise ratio (SNR increases and is above the threshold value, it will lie very close to Cramer-Rao lower bound (CRLB, which is dependent on the number of DFT points. However, its mean square error (MSE performance is directly proportional to its calculation cost. As a modified version of support vector regression (SVR, least squares SVR (LS-SVR can not only still keep excellent capabilities for generalizing and fitting but also exhibit lower computational complexity. In this paper, therefore, LS-SVR is employed to interpolate on Fourier coefficients of received signals and attain high frequency estimation accuracy. Our results show that the proposed algorithm can make a good compromise between calculation cost and MSE performance under the assumption that the sample size, number of DFT points, and resampling points are already known.

  7. Stability analysis of the Peregrine solution via squared eigenfunctions

    Science.gov (United States)

    Schober, C. M.; Strawn, M.

    2017-10-01

    A preliminary numerical investigation involving ensembles of perturbed initial data for the Peregrine soliton (the lowest order rational solution of the nonlinear Schrödinger equation) indicates that it is unstable [16]. In this paper we analytically investigate the linear stability of the Peregrine soliton, appealing to the fact that the Peregrine solution can be viewed as the singular limit of a single mode spatially periodic breathers (SPB). The "squared eigenfunction" connection between the Zakharov-Shabat (Z-S) system and the linearized NLS equation is employed in the stability analysis. Specifically, we determine the eigenfunctions of the Z-S system associated with the Peregrine soliton and construct a family of solutions of the associated linearized NLS (about the Peregrine) in terms of quadratic products of components of the eigenfunctions (i.e., the squared eigenfunction). We find there exist solutions of the linearization that grow exponentially in time, thus showing the Peregrine soliton is linearly unstable.

  8. Sub-Millimeter Tests of the Newtonian Inverse Square Law

    International Nuclear Information System (INIS)

    Adelberger, Eric

    2005-01-01

    It is remarkable that small-scale experiments can address important open issues in fundamental science such as: 'why is gravity so weak compared to the other interactions?' and 'why is the cosmological constant so small compared to the predictions of quantum mechanics?' String theory ideas (new scalar particles and extra dimensions) and other notions hint that Newton's Inverse-Square Law could break down at distances less than 1 mm. I will review some motivations for testing the Inverse-Square Law, and discuss recent mechanical experiments with torsion balances, small-scillators, micro-cantilevers, and ultra-cold neutrons. Our torsion-balance experiments have probed for gravitational-strength interactions with length scales down to 70 micrometers, which is approximately the diameter of a human hair.

  9. Quantum dynamics of relativistic bosons through nonminimal vector square potentials

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Luiz P. de, E-mail: oliveira.phys@gmail.com

    2016-09-15

    The dynamics of relativistic bosons (scalar and vectorial) through nonminimal vector square (well and barrier) potentials is studied in the Duffin–Kemmer–Petiau (DKP) formalism. We show that the problem can be mapped in effective Schrödinger equations for a component of the DKP spinor. An oscillatory transmission coefficient is found and there is total reflection. Additionally, the energy spectrum of bound states is obtained and reveals the Schiff–Snyder–Weinberg effect, for specific conditions the potential lodges bound states of particles and antiparticles. - Highlights: • DKP bosons in a nonminimal vector square potential are studied. • Spin zero and spin one bosons have the same results. • The Schiff–Snyder–Weinberg effect is observed.

  10. Source allocation by least-squares hydrocarbon fingerprint matching

    Energy Technology Data Exchange (ETDEWEB)

    William A. Burns; Stephen M. Mudge; A. Edward Bence; Paul D. Boehm; John S. Brown; David S. Page; Keith R. Parker [W.A. Burns Consulting Services LLC, Houston, TX (United States)

    2006-11-01

    There has been much controversy regarding the origins of the natural polycyclic aromatic hydrocarbon (PAH) and chemical biomarker background in Prince William Sound (PWS), Alaska, site of the 1989 Exxon Valdez oil spill. Different authors have attributed the sources to various proportions of coal, natural seep oil, shales, and stream sediments. The different probable bioavailabilities of hydrocarbons from these various sources can affect environmental damage assessments from the spill. This study compares two different approaches to source apportionment with the same data (136 PAHs and biomarkers) and investigate whether increasing the number of coal source samples from one to six increases coal attributions. The constrained least-squares (CLS) source allocation method that fits concentrations meets geologic and chemical constraints better than partial least-squares (PLS) which predicts variance. The field data set was expanded to include coal samples reported by others, and CLS fits confirm earlier findings of low coal contributions to PWS. 15 refs., 5 figs.

  11. Least-Square Prediction for Backward Adaptive Video Coding

    Directory of Open Access Journals (Sweden)

    Li Xin

    2006-01-01

    Full Text Available Almost all existing approaches towards video coding exploit the temporal redundancy by block-matching-based motion estimation and compensation. Regardless of its popularity, block matching still reflects an ad hoc understanding of the relationship between motion and intensity uncertainty models. In this paper, we present a novel backward adaptive approach, named "least-square prediction" (LSP, and demonstrate its potential in video coding. Motivated by the duality between edge contour in images and motion trajectory in video, we propose to derive the best prediction of the current frame from its causal past using least-square method. It is demonstrated that LSP is particularly effective for modeling video material with slow motion and can be extended to handle fast motion by temporal warping and forward adaptation. For typical QCIF test sequences, LSP often achieves smaller MSE than , full-search, quarter-pel block matching algorithm (BMA without the need of transmitting any overhead.

  12. Least squares orthogonal polynomial approximation in several independent variables

    International Nuclear Information System (INIS)

    Caprari, R.S.

    1992-06-01

    This paper begins with an exposition of a systematic technique for generating orthonormal polynomials in two independent variables by application of the Gram-Schmidt orthogonalization procedure of linear algebra. It is then demonstrated how a linear least squares approximation for experimental data or an arbitrary function can be generated from these polynomials. The least squares coefficients are computed without recourse to matrix arithmetic, which ensures both numerical stability and simplicity of implementation as a self contained numerical algorithm. The Gram-Schmidt procedure is then utilised to generate a complete set of orthogonal polynomials of fourth degree. A theory for the transformation of the polynomial representation from an arbitrary basis into the familiar sum of products form is presented, together with a specific implementation for fourth degree polynomials. Finally, the computational integrity of this algorithm is verified by reconstructing arbitrary fourth degree polynomials from their values at randomly chosen points in their domain. 13 refs., 1 tab

  13. Arts@CERN | ACCELERATE Austria | 19 May | IdeaSquare

    CERN Multimedia

    2016-01-01

    ​Arts@CERN welcomes you to a talk by architects Sandra Manninger and Matias Del Campo, at IdeaSquare (Point 1) on May 19 at 6:00 p.m.   Sensible Bodies - architecture, data, and desire. Sandra and Matias are the winning architects for ACCELERATE Austria. Focusing on the notion of geometry, they are at CERN during the month of May, as artists in residence. Their research highlights how to go beyond beautiful data to discover something that could be defined voluptuous data. This coagulation of numbers, algorithms, procedures and programs uses the forces of thriving nature and, passing through the calculation of a multi-core processor, knits them with human desire. Read more. ACCELERATE Austria is supported by The Department of Arts of the Federal Chancellery of Austria. Thursday, May 19 at 6:00 p.m. at IdeaSquare.  See event on Indico. 

  14. The central subgroup of the nonabelian tensor square of Bieberbach ...

    African Journals Online (AJOL)

    A Bieberbach group with point group C2 xC2 is a free torsion crystallographic group. A central subgroup of a nonabelian tensor square of a group G, denoted by ∇(G) is a normal subgroup generated by generator g⊗g for all g∈G and essentially depends on the abelianization of the group. In this paper, the formula of the ...

  15. Anisotropic square lattice Potts ferromagnet: renormalization group treatment

    International Nuclear Information System (INIS)

    Oliveira, P.M.C. de; Tsallis, C.

    1981-01-01

    The choice of a convenient self-dual cell within a real space renormalization group framework enables a satisfactory treatment of the anisotropic square lattice q-state Potts ferromagnet criticality. The exact critical frontier and dimensionality crossover exponent PHI as well as the expected universality behaviour (renormalization flow sense) are recovered for any linear scaling factor b and all values of q(q - [pt

  16. Regularized Partial Least Squares with an Application to NMR Spectroscopy

    OpenAIRE

    Allen, Genevera I.; Peterson, Christine; Vannucci, Marina; Maletic-Savatic, Mirjana

    2012-01-01

    High-dimensional data common in genomics, proteomics, and chemometrics often contains complicated correlation structures. Recently, partial least squares (PLS) and Sparse PLS methods have gained attention in these areas as dimension reduction techniques in the context of supervised data analysis. We introduce a framework for Regularized PLS by solving a relaxation of the SIMPLS optimization problem with penalties on the PLS loadings vectors. Our approach enjoys many advantages including flexi...

  17. Algebraic K-theory and sums-of-squares formulas

    OpenAIRE

    Dugger, Daniel; Isaksen, Daniel C.

    2004-01-01

    We prove a result about the non-existence of certain sums-of-squares formulas over a field. This generalizes an old theorem which used topological K-theory to obtain obstruction conditions when the field is the real numbers. Our result applies to arbitrary fields not of characteristic 2, making use of algebraic K-theory in place of topological K-theory.

  18. Market Structure and Competitive Strategy in Market Square

    Institute of Scientific and Technical Information of China (English)

    PENG Juanjuan

    2007-01-01

    Market Square shopping center contains several restaurants and cafés providing a diverse range of Asian foods and delicacies and this area is known by locals and Griffith University students as a great location for 'eating out'. Then, what is the market structure in this shopping mall and what kind of competitive strategies should be used to maximize profits according to the characteristics in this shopping center?

  19. Covering an uncountable square by countable many continuous functions

    Czech Academy of Sciences Publication Activity Database

    Kubiś, Wieslaw; Vejnar, B.

    2012-01-01

    Roč. 140, č. 12 (2012), s. 4359-4368 ISSN 0002-9939 R&D Projects: GA AV ČR IAA100190901 Institutional research plan: CEZ:AV0Z10190503 Keywords : uncountable square * covering by continuous functions * set of cardinality N-1 Subject RIV: BA - General Mathematics Impact factor: 0.609, year: 2012 http://www.ams.org/journals/proc/2012-140-12/S0002-9939-2012-11292-4/home.html

  20. Dose rate from the square volume radiation source

    International Nuclear Information System (INIS)

    Karpov, V.I.

    1978-01-01

    The expression for determining the dose rate from a three-dimensional square flat-parallel source of any dimensions is obtained. A simplified method for integrating the resultant expression is proposed. A comparison of the calculation results with the results by the Monte Carlo method has shown them to coincide within 6-8%. Since buildings and structures consist of rectangular elements, the method is recommended for practical calculations of dose rates in residential buildings

  1. Adaptive Noise Canceling Menggunakan Algoritma Least Mean Square (Lms)

    OpenAIRE

    Nardiana, Anita; Sumaryono, Sari Sujoko

    2011-01-01

    Noise is inevitable in communication system. In some cases, noise can disturb signal. It is veryannoying as the received signal is jumbled with the noise itself. To reduce or remove noise, filter lowpass,highpass or bandpass can solve the problems, but this method cannot reach a maximum standard. One ofthe alternatives to solve the problem is by using adaptive filter. Adaptive algorithm frequently used is LeastMean Square (LMS) Algorithm which is compatible to Finite Impulse Response (FIR). T...

  2. Capillary condensation in a square geometry with surface fields.

    Science.gov (United States)

    Zubaszewska, M; Gendiar, A; Drzewiński, A

    2012-12-01

    We study the influence of wetting on capillary condensation for a simple fluid in a square geometry with surface fields, where the reference system is an infinitely long slit. The corner transfer matrix renormalization group method has been extended to study a two-dimensional Ising model confined in an L × L geometry with equal surface fields. Our results have confirmed that in both geometries the coexistence line shift is governed by the same scaling powers, but their prefactors are different.

  3. A FORTRAN program for a least-square fitting

    International Nuclear Information System (INIS)

    Yamazaki, Tetsuo

    1978-01-01

    A practical FORTRAN program for a least-squares fitting is presented. Although the method is quite usual, the program calculates not only the most satisfactory set of values of unknowns but also the plausible errors associated with them. As an example, a measured lateral absorbed-dose distribution in water for a narrow 25-MeV electron beam is fitted to a Gaussian distribution. (auth.)

  4. Analysis of quantile regression as alternative to ordinary least squares

    OpenAIRE

    Ibrahim Abdullahi; Abubakar Yahaya

    2015-01-01

    In this article, an alternative to ordinary least squares (OLS) regression based on analytical solution in the Statgraphics software is considered, and this alternative is no other than quantile regression (QR) model. We also present goodness of fit statistic as well as approximate distributions of the associated test statistics for the parameters. Furthermore, we suggest a goodness of fit statistic called the least absolute deviation (LAD) coefficient of determination. The procedure is well ...

  5. Tunnelling of plane waves through a square barrier

    Energy Technology Data Exchange (ETDEWEB)

    Julve, J [IMAFF, Consejo Superior de Investigaciones CientIficas, Serrano 113 bis, Madrid 28006 (Spain); UrrIes, F J de [Departamento de Fisica, Universidad de Alcala de Henares, Alcala de Henares, Madrid (Spain)], E-mail: julve@imaff.cfmac.csic.es, E-mail: fernando.urries@uah.es

    2008-08-01

    The time evolution of plane waves in the presence of a one-dimensional square quantum barrier is considered. Comparison is made between the cases of an infinite and a cut-off (shutter) initial plane wave. The difference is relevant when the results are applied to the analysis of the tunnelling regime. This work is focused on the analytical calculation of the time-evolved solution and highlights the contribution of the resonant (Gamow) states.

  6. Earthquake Source Spectral Study beyond the Omega-Square Model

    Science.gov (United States)

    Uchide, T.; Imanishi, K.

    2017-12-01

    Earthquake source spectra have been used for characterizing earthquake source processes quantitatively and, at the same time, simply, so that we can analyze the source spectra for many earthquakes, especially for small earthquakes, at once and compare them each other. A standard model for the source spectra is the omega-square model, which has the flat spectrum and the falloff inversely proportional to the square of frequencies at low and high frequencies, respectively, which are bordered by a corner frequency. The corner frequency has often been converted to the stress drop under the assumption of circular crack models. However, recent studies claimed the existence of another corner frequency [Denolle and Shearer, 2016; Uchide and Imanishi, 2016] thanks to the recent development of seismic networks. We have found that many earthquakes in areas other than the area studied by Uchide and Imanishi [2016] also have source spectra deviating from the omega-square model. Another part of the earthquake spectra we now focus on is the falloff rate at high frequencies, which will affect the seismic energy estimation [e.g., Hirano and Yagi, 2017]. In June, 2016, we deployed seven velocity seismometers in the northern Ibaraki prefecture, where the shallow crustal seismicity mainly with normal-faulting events was activated by the 2011 Tohoku-oki earthquake. We have recorded seismograms at 1000 samples per second and at a short distance from the source, so that we can investigate the high-frequency components of the earthquake source spectra. Although we are still in the stage of discovery and confirmation of the deviation from the standard omega-square model, the update of the earthquake source spectrum model will help us systematically extract more information on the earthquake source process.

  7. Multisplitting for linear, least squares and nonlinear problems

    Energy Technology Data Exchange (ETDEWEB)

    Renaut, R.

    1996-12-31

    In earlier work, presented at the 1994 Iterative Methods meeting, a multisplitting (MS) method of block relaxation type was utilized for the solution of the least squares problem, and nonlinear unconstrained problems. This talk will focus on recent developments of the general approach and represents joint work both with Andreas Frommer, University of Wupertal for the linear problems and with Hans Mittelmann, Arizona State University for the nonlinear problems.

  8. Multi-source least-squares reverse time migration

    KAUST Repository

    Dai, Wei

    2012-06-15

    Least-squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least-squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase-encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least-squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model. © 2012 European Association of Geoscientists & Engineers.

  9. Bounded Perturbation Regularization for Linear Least Squares Estimation

    KAUST Repository

    Ballal, Tarig

    2017-10-18

    This paper addresses the problem of selecting the regularization parameter for linear least-squares estimation. We propose a new technique called bounded perturbation regularization (BPR). In the proposed BPR method, a perturbation with a bounded norm is allowed into the linear transformation matrix to improve the singular-value structure. Following this, the problem is formulated as a min-max optimization problem. Next, the min-max problem is converted to an equivalent minimization problem to estimate the unknown vector quantity. The solution of the minimization problem is shown to converge to that of the ℓ2 -regularized least squares problem, with the unknown regularizer related to the norm bound of the introduced perturbation through a nonlinear constraint. A procedure is proposed that combines the constraint equation with the mean squared error (MSE) criterion to develop an approximately optimal regularization parameter selection algorithm. Both direct and indirect applications of the proposed method are considered. Comparisons with different Tikhonov regularization parameter selection methods, as well as with other relevant methods, are carried out. Numerical results demonstrate that the proposed method provides significant improvement over state-of-the-art methods.

  10. Twin edge colorings of certain square graphs and product graphs

    Directory of Open Access Journals (Sweden)

    R Rajarajachozhan

    2016-04-01

    Full Text Available A twin edge $k\\!$-coloring of a graph $G$ is a proper edge $k$-coloring of $G$ with the elements of $\\mathbb{Z}_k$ so that the induced vertex $k$-coloring, in which the color of a vertex $v$ in $G$ is the sum in $\\mathbb{Z}_k$ of the colors of the edges incident with $v,$ is a proper vertex $k\\!$-coloring. The minimum $k$ for which $G$ has a twin edge $k\\!$-coloring is called the twin chromatic index of $G.$ Twin chromatic index of the square $P_n^2,$ $n\\ge 4,$ and the square $C_n^2,$ $n\\ge 6,$ are determined. In fact, the twin chromatic index of the square $C_7^2$ is $\\Delta+2,$ where $\\Delta$ is the maximum degree. Twin chromatic index of $C_m\\,\\Box\\,P_n$ is determined, where $\\Box$ denotes the Cartesian product. $C_r$ and $P_r$ are, respectively, the cycle, and the path on $r$ vertices each.

  11. Multi-source least-squares reverse time migration

    KAUST Repository

    Dai, Wei; Fowler, Paul J.; Schuster, Gerard T.

    2012-01-01

    Least-squares migration has been shown to improve image quality compared to the conventional migration method, but its computational cost is often too high to be practical. In this paper, we develop two numerical schemes to implement least-squares migration with the reverse time migration method and the blended source processing technique to increase computation efficiency. By iterative migration of supergathers, which consist in a sum of many phase-encoded shots, the image quality is enhanced and the crosstalk noise associated with the encoded shots is reduced. Numerical tests on 2D HESS VTI data show that the multisource least-squares reverse time migration (LSRTM) algorithm suppresses migration artefacts, balances the amplitudes, improves image resolution and reduces crosstalk noise associated with the blended shot gathers. For this example, the multisource LSRTM is about three times faster than the conventional RTM method. For the 3D example of the SEG/EAGE salt model, with a comparable computational cost, multisource LSRTM produces images with more accurate amplitudes, better spatial resolution and fewer migration artefacts compared to conventional RTM. The empirical results suggest that multisource LSRTM can produce more accurate reflectivity images than conventional RTM does with a similar or less computational cost. The caveat is that the LSRTM image is sensitive to large errors in the migration velocity model. © 2012 European Association of Geoscientists & Engineers.

  12. Optimization of the geometrical stability in square ring laser gyroscopes

    International Nuclear Information System (INIS)

    Santagata, R; Beghi, A; Cuccato, D; Belfi, J; Beverini, N; Virgilio, A Di; Ortolan, A; Porzio, A; Solimeno, S

    2015-01-01

    Ultra-sensitive ring laser gyroscopes are regarded as potential detectors of the general relativistic frame-dragging effect due to the rotation of the Earth. Our project for this goal is called GINGER (gyroscopes in general relativity), and consists of a ground-based triaxial array of ring lasers aimed at measuring the rotation rate of the Earth with an accuracy of 10 −14 rad s −1 . Such an ambitious goal is now within reach, as large-area ring lasers are very close to the required sensitivity and stability. However, demanding constraints on the geometrical stability of the optical path of the laser inside the ring cavity are required. Thus, we have begun a detailed study of the geometry of an optical cavity in order to find a control strategy for its geometry that could meet the specifications of the GINGER project. As the cavity perimeter has a stationary point for the square configuration, we identify a set of transformations on the mirror positions that allows us to adjust the laser beam steering to the shape of a square. We show that the geometrical stability of a square cavity strongly increases by implementing a suitable system to measure the mirror distances, and that the geometry stabilization can be achieved by measuring the absolute lengths of the two diagonals and the perimeter of the ring. (paper)

  13. Solving linear inequalities in a least squares sense

    Energy Technology Data Exchange (ETDEWEB)

    Bramley, R.; Winnicka, B. [Indiana Univ., Bloomington, IN (United States)

    1994-12-31

    Let A {element_of} {Re}{sup mxn} be an arbitrary real matrix, and let b {element_of} {Re}{sup m} a given vector. A familiar problem in computational linear algebra is to solve the system Ax = b in a least squares sense; that is, to find an x* minimizing {parallel}Ax {minus} b{parallel}, where {parallel} {center_dot} {parallel} refers to the vector two-norm. Such an x* solves the normal equations A{sup T}(Ax {minus} b) = 0, and the optimal residual r* = b {minus} Ax* is unique (although x* need not be). The least squares problem is usually interpreted as corresponding to multiple observations, represented by the rows of A and b, on a vector of data x. The observations may be inconsistent, and in this case a solution is sought that minimizes the norm of the residuals. A less familiar problem to numerical linear algebraists is the solution of systems of linear inequalities Ax {le} b in a least squares sense, but the motivation is similar: if a set of observations places upper or lower bounds on linear combinations of variables, the authors want to find x* minimizing {parallel} (Ax {minus} b){sub +} {parallel}, where the i{sup th} component of the vector v{sub +} is the maximum of zero and the i{sup th} component of v.

  14. Beyond the Manual Channel

    DEFF Research Database (Denmark)

    , the main focus there is on spoken languages in their written and spoken forms. This series of workshops, however, offers a forum for researchers focussing on sign languages. For the fourth time, the workshop had sign language corpora as its main topic. This time, the focus was on any aspect beyond...... the manual channel. Not surprisingly, most papers deal with non-manuals on the face. Once again, the papers at this workshop clearly identify the potentials of even closer cooperation between sign linguists and sign language engineers, and we think it is events like this that contribute a lot to a better...

  15. Ion Channels in Leukocytes

    Science.gov (United States)

    1991-07-01

    muscle k142), heart muscle (80), bo- are released. In recent years much has been learned vine pulmonar arter endothelial cells (251), and rat about the...b3 Zn or cytes from cystic fibrosis patients lack a Cl current that Ni (1 mM)-added to the cytoplasmic side of the mem- can be acti% ated b3 the...that at37’C hu- to be defectiv.- in cystic fibrosis (55, 277), and Chen et al. man T-cell CiL channels are active at rest, implies that (25) have shown

  16. A Micromechanical RF Channelizer

    Science.gov (United States)

    Akgul, Mehmet

    The power consumption of a radio generally goes as the number and strength of the RF signals it must process. In particular, a radio receiver would consume much less power if the signal presented to its electronics contained only the desired signal in a tiny percent bandwidth frequency channel, rather than the typical mix of signals containing unwanted energy outside the desired channel. Unfortunately, a lack of filters capable of selecting single channel bandwidths at RF forces the front-ends of contemporary receivers to accept unwanted signals, and thus, to operate with sub-optimal efficiency. This dissertation focuses on the degree to which capacitive-gap transduced micromechanical resonators can achieve the aforementioned RF channel-selecting filters. It aims to first show theoretically that with appropriate scaling capacitive-gap transducers are strong enough to meet the needed coupling requirements; and second, to fully detail an architecture and design procedure needed to realize said filters. Finally, this dissertation provides an actual experimentally demonstrated RF channel-select filter designed using the developed procedures and confirming theoretical predictions. Specifically, this dissertation introduces four methods that make possible the design and fabrication of RF channel-select filters. The first of these introduces a small-signal equivalent circuit for parallel-plate capacitive-gap transduced micromechanical resonators that employs negative capacitance to model the dependence of resonance frequency on electrical stiffness in a way that facilitates the analysis of micromechanical circuits loaded with arbitrary electrical impedances. The new circuit model not only correctly predicts the dependence of electrical stiffness on the impedances loading the input and output electrodes of parallel-plate capacitive-gap transduced micromechanical device, but does so in a visually intuitive way that identifies current drive as most appropriate for

  17. TRPV6 channels.

    Science.gov (United States)

    Fecher-Trost, Claudia; Weissgerber, Petra; Wissenbach, Ulrich

    2014-01-01

    TRPV6 (former synonyms ECAC2, CaT1, CaT-like) displays several specific features which makes it unique among the members of the mammalian Trp gene family (1) TRPV6 (and its closest relative, TRPV5) are the only highly Ca(2+)-selective channels of the entire TRP superfamily (Peng et al. 1999; Wissenbach et al. 2001; Voets et al. 2004). (2) Translation of Trpv6 initiates at a non-AUG codon, at ACG, located upstream of the annotated AUG, which is not used for initiation (Fecher-Trost et al. 2013). The ACG codon is nevertheless decoded by methionine. Not only a very rare event in eukaryotic biology, the full-length TRPV6 protein existing in vivo comprises an amino terminus extended by 40 amino acid residues compared to the annotated truncated TRPV6 protein which has been used in most studies on TRPV6 channel activity so far. (In the following numbering occurs according to this full-length protein, with the numbers of the so far annotated truncated protein in brackets). (3) Only in humans a coupled polymorphism of Trpv6 exists causing three amino acid exchanges and resulting in an ancestral Trpv6 haplotype and a so-called derived Trpv6 haplotype (Wissenbach et al. 2001). The ancestral allele encodes the amino acid residues C197(157), M418(378) and M721(681) and the derived alleles R197(157), V418(378) and T721(681). The ancestral haplotype is found in all species, the derived Trpv6 haplotype has only been identified in humans, and its frequency increases with the distance to the African continent. Apparently the Trpv6 gene has been a strong target for selection in humans, and its derived variant is one of the few examples showing consistently differences to the orthologues genes of other primates (Akey et al. 2004, 2006; Stajich and Hahn 2005; Hughes et al. 2008). (4) The Trpv6 gene expression is significantly upregulated in several human malignancies including the most common cancers, prostate and breast cancer (Wissenbach et al. 2001; Zhuang et al. 2002; Fixemer et al

  18. Superimposed Training-Based Channel Estimation for MIMO Relay Networks

    Directory of Open Access Journals (Sweden)

    Xiaoyan Xu

    2012-01-01

    Full Text Available We introduce the superimposed training strategy into the multiple-input multiple-output (MIMO amplify-and-forward (AF one-way relay network (OWRN to perform the individual channel estimation at the destination. Through the superposition of a group of additional training vectors at the relay subject to power allocation, the separated estimates of the source-relay and relay-destination channels can be obtained directly at the destination, and the accordance with the two-hop AF strategy can be guaranteed at the same time. The closed-form Bayesian Cramér-Rao lower bound (CRLB is derived for the estimation of two sets of flat-fading MIMO channel under random channel parameters and further exploited to design the optimal training vectors. A specific suboptimal channel estimation algorithm is applied in the MIMO AF OWRN using the optimal training sequences, and the normalized mean square error performance for the estimation is provided to verify the Bayesian CRLB results.

  19. Channel estimation in few mode fiber mode division multiplexing transmission system

    Science.gov (United States)

    Hei, Yongqiang; Li, Li; Li, Wentao; Li, Xiaohui; Shi, Guangming

    2018-03-01

    It is abundantly clear that obtaining the channel state information (CSI) is of great importance for the equalization and detection in coherence receivers. However, to the best of the authors' knowledge, in most of the existing literatures, CSI is assumed to be perfectly known at the receiver. So far, few literature discusses the effects of imperfect CSI on MDM system performance caused by channel estimation. Motivated by that, in this paper, the channel estimation in few mode fiber (FMF) mode division multiplexing (MDM) system is investigated, in which two classical channel estimation methods, i.e., least square (LS) method and minimum mean square error (MMSE) method, are discussed with the assumption of the spatially white noise lumped at the receiver side of MDM system. Both the capacity and BER performance of MDM system affected by mode-dependent gain or loss (MDL) with different channel estimation errors have been studied. Simulation results show that the capacity and BER performance can be further deteriorated in MDM system by the channel estimation, and an 1e-3 variance of channel estimation error is acceptable in MDM system with 0-6 dB MDL values.

  20. Penalized linear regression for discrete ill-posed problems: A hybrid least-squares and mean-squared error approach

    KAUST Repository

    Suliman, Mohamed Abdalla Elhag

    2016-12-19

    This paper proposes a new approach to find the regularization parameter for linear least-squares discrete ill-posed problems. In the proposed approach, an artificial perturbation matrix with a bounded norm is forced into the discrete ill-posed model matrix. This perturbation is introduced to enhance the singular-value (SV) structure of the matrix and hence to provide a better solution. The proposed approach is derived to select the regularization parameter in a way that minimizes the mean-squared error (MSE) of the estimator. Numerical results demonstrate that the proposed approach outperforms a set of benchmark methods in most cases when applied to different scenarios of discrete ill-posed problems. Jointly, the proposed approach enjoys the lowest run-time and offers the highest level of robustness amongst all the tested methods.

  1. Mimicking multi-channel scattering with single-channel approaches

    OpenAIRE

    Grishkevich, Sergey; Schneider, Philipp-Immanuel; Vanne, Yulian V.; Saenz, Alejandro

    2009-01-01

    The collision of two atoms is an intrinsic multi-channel (MC) problem as becomes especially obvious in the presence of Feshbach resonances. Due to its complexity, however, single-channel (SC) approximations, which reproduce the long-range behavior of the open channel, are often applied in calculations. In this work the complete MC problem is solved numerically for the magnetic Feshbach resonances (MFRs) in collisions between generic ultracold 6Li and 87Rb atoms in the ground state and in the ...

  2. PERFORMANCE OF THE ZERO FORCING PRECODING MIMO BROADCAST SYSTEMS WITH CHANNEL ESTIMATION ERRORS

    Institute of Scientific and Technical Information of China (English)

    Wang Jing; Liu Zhanli; Wang Yan; You Xiaohu

    2007-01-01

    In this paper, the effect of channel estimation errors upon the Zero Forcing (ZF) precoding Multiple Input Multiple Output Broadcast (MIMO BC) systems was studied. Based on the two kinds of Gaussian estimation error models, the performance analysis is conducted under different power allocation strategies. Analysis and simulation show that if the covariance of channel estimation errors is independent of the received Signal to Noise Ratio (SNR), imperfect channel knowledge deteriorates the sum capacity and the Bit Error Rate (BER) performance severely. However, under the situation of orthogonal training and the Minimum Mean Square Error (MMSE) channel estimation, the sum capacity and BER performance are consistent with those of the perfect Channel State Information (CSI)with only a performance degradation.

  3. Channel and delay estimation for base-station–based cooperative communications in frequency-selective fading channels

    Directory of Open Access Journals (Sweden)

    Hongjun Xu

    2011-07-01

    Full Text Available A channel and delay estimation algorithm for both positive and negative delay, based on the distributed Alamouti scheme, has been recently discussed for base-station–based asynchronous cooperative systems in frequency-flat fading channels. This paper extends the algorithm, the maximum likelihood estimator, to work in frequency-selective fading channels. The minimum mean square error (MMSE performance of channel estimation for both packet schemes and normal schemes is discussed in this paper. The symbol error rate (SER performance of equalisation and detection for both time-reversal space-time block code (STBC and single-carrier STBC is also discussed in this paper. The MMSE simulation results demonstrated the superior performance of the packet scheme over the normal scheme with an improvement in performance of up to 6 dB when feedback was used in the frequency-selective channel at a MSE of 3 x 10–2. The SER simulation results showed that, although both the normal and packet schemes achieved similar diversity orders, the packet scheme demonstrated a 1 dB coding gain over the normal scheme at a SER of 10–5. Finally, the SER simulations showed that the frequency-selective fading system outperformed the frequency-flat fading system.

  4. Turbulent heat transfer and nanofluid flow in a protruded ribbed square passage

    Science.gov (United States)

    Kumar, Sunil; Kothiyal, Alok Darshan; Bisht, Mangal Singh; Kumar, Anil

    In this article, turbulent heat transfer of nanofluid flow in square passage with protruded rib shape is numerically and experimentally studied over Reynolds number ranges of 4000-18000. Different nanoparticles (Al2O3, CuO, and ZnO), with different concentration (φ) range of 1-4% and different nanoparticle diameter (dnp) range of 30-45 nm are disperse in water (base fluid). Several parameters such as stream wise distance (Xs /dp) range of 1.4-2.6, span wise distance (Ys /dp) range of 1.4-2.6, ratio of protruded height to print diameter (ep /dp) range of 0.83-1.67 also studied to find the consequence on thermal and hydrodynamic characteristics. Simulations were carried out to obtain heat and fluid flow behaviour of smooth and ribbed square channel using commercial CFD software, ANSYS 15.0 (Fluent). Renormalization k - ε model was employed to assess the influence of protruded ribs on turbulent flow and velocity field. The outcome indicates that Al2O3 nanofluid has the highest value of average Nusselt number as compare to other nanofluids. The average Nusselt number increases as the concentration increases and it decreases as nanoparticle diameter increases. The thermal hydrodynamic performance parameter based on equal pumping power, average Nusselt number and average friction factor were found to be highest for Al2O3, φ = 0.04, dnp = 30 nm, Xs /dp = 1.8, Ys /dp = 1.8 and ep /dp = 1.0 . The numerical data are compared with the corresponding experimental data. Comparison between CFD and experimental analysis results showed that good agreement as the data fell within ±7.0% error band.

  5. Estimasi Kanal Akustik Bawah Air Untuk Perairan Dangkal Menggunakan Metode Least Square (LS dan Minimum Mean Square Error (MMSE

    Directory of Open Access Journals (Sweden)

    Mardawia M Panrereng

    2015-06-01

    Full Text Available Dalam beberapa tahun terakhir, sistem komunikasi akustik bawah air banyak dikembangkan oleh beberapa peneliti. Besarnya tantangan yang dihadapi membuat para peneliti semakin tertarik untuk mengembangkan penelitian dibidang ini. Kanal bawah air merupakan media komunikasi yang sulit karena adanya attenuasi, absorption, dan multipath yang disebabkan oleh gerakan gelombang air setiap saat. Untuk perairan dangkal, multipath disebabkan adanya pantulan dari permukaan dan dasar laut. Kebutuhan pengiriman data cepat dengan bandwidth terbatas menjadikan Ortogonal Frequency Division Multiplexing (OFDM sebagai solusi untuk komunikasi transmisi tinggi dengan modulasi menggunakan Binary Phase-Shift Keying (BPSK. Estimasi kanal bertujuan untuk mengetahui karakteristik respon impuls kanal propagasi dengan mengirimkan pilot simbol. Pada estimasi kanal menggunakan metode Least Square (LS nilai Mean Square Error (MSE yang diperoleh cenderung lebih besar dari metode estimasi kanal menggunakan metode Minimum Mean Square (MMSE. Hasil kinerja estimasi kanal berdasarkan perhitungan Bit Error Rate (BER untuk estimasi kanal menggunakan metode LS dan metode MMSE tidak menunjukkan perbedaan yang signifikan yaitu berselisih satu SNR untuk setiap metode estimasi kanal yang digunakan.

  6. Mean square stabilization and mean square exponential stabilization of stochastic BAM neural networks with Markovian jumping parameters

    International Nuclear Information System (INIS)

    Ye, Zhiyong; Zhang, He; Zhang, Hongyu; Zhang, Hua; Lu, Guichen

    2015-01-01

    Highlights: •This paper introduces a non-conservative Lyapunov functional. •The achieved results impose non-conservative and can be widely used. •The conditions are easily checked by the Matlab LMI Tool Box. The desired state feedback controller can be well represented by the conditions. -- Abstract: This paper addresses the mean square exponential stabilization problem of stochastic bidirectional associative memory (BAM) neural networks with Markovian jumping parameters and time-varying delays. By establishing a proper Lyapunov–Krasovskii functional and combining with LMIs technique, several sufficient conditions are derived for ensuring exponential stabilization in the mean square sense of such stochastic BAM neural networks. In addition, the achieved results are not difficult to verify for determining the mean square exponential stabilization of delayed BAM neural networks with Markovian jumping parameters and impose less restrictive and less conservative than the ones in previous papers. Finally, numerical results are given to show the effectiveness and applicability of the achieved results

  7. A survey on OFDM channel estimation techniques based on denoising strategies

    Directory of Open Access Journals (Sweden)

    Pallaviram Sure

    2017-04-01

    Full Text Available Channel estimation forms the heart of any orthogonal frequency division multiplexing (OFDM based wireless communication receiver. Frequency domain pilot aided channel estimation techniques are either least squares (LS based or minimum mean square error (MMSE based. LS based techniques are computationally less complex. Unlike MMSE ones, they do not require a priori knowledge of channel statistics (KCS. However, the mean square error (MSE performance of the channel estimator incorporating MMSE based techniques is better compared to that obtained with the incorporation of LS based techniques. To enhance the MSE performance using LS based techniques, a variety of denoising strategies have been developed in the literature, which are applied on the LS estimated channel impulse response (CIR. The advantage of denoising threshold based LS techniques is that, they do not require KCS but still render near optimal MMSE performance similar to MMSE based techniques. In this paper, a detailed survey on various existing denoising strategies, with a comparative discussion of these strategies is presented.

  8. Multiplicative properties of quantum channels

    Science.gov (United States)

    Rahaman, Mizanur

    2017-08-01

    In this paper, we study the multiplicative behaviour of quantum channels, mathematically described by trace preserving, completely positive maps on matrix algebras. It turns out that the multiplicative domain of a unital quantum channel has a close connection to its spectral properties. A structure theorem (theorem 2.5), which reveals the automorphic property of an arbitrary unital quantum channel on a subalgebra, is presented. Various classes of quantum channels (irreducible, primitive, etc) are then analysed in terms of this stabilising subalgebra. The notion of the multiplicative index of a unital quantum channel is introduced, which measures the number of times a unital channel needs to be composed with itself for the multiplicative algebra to stabilise. We show that the maps that have trivial multiplicative domains are dense in completely bounded norm topology in the set of all unital completely positive maps. Some applications in quantum information theory are discussed.

  9. Networked control of discrete-time linear systems over lossy digital communication channels

    Science.gov (United States)

    Jin, Fang; Zhao, Guang-Rong; Liu, Qing-Quan

    2013-12-01

    This article addresses networked control problems for linear time-invariant systems. The insertion of the digital communication network inevitably leads to packet dropout, time delay and quantisation error. Due to data rate limitations, quantisation error is not neglected. In particular, the case where the sensors and controllers are geographically separated and connected via noisy, bandwidth-limited digital communication channels is considered. A fundamental limitation on the data rate of the channel for mean-square stabilisation of the closed-loop system is established. Sufficient conditions for mean-square stabilisation are derived. It is shown that there exists a quantisation, coding and control scheme to stabilise the unstable system over packet dropout communication channels if the data rate is larger than the lower bound proposed in our result. An illustrative example is given to demonstrate the effectiveness of the proposed conditions.

  10. A multi-channel isolated power supply in non-equipotential circuit

    Science.gov (United States)

    Li, Xiang; Zhao, Bo-Wen; Zhang, Yan-Chi; Xie, Da

    2018-04-01

    A multi-channel isolation power supply is designed for the problems of different MOSFET or IGBT in the non-equipotential circuit in this paper. It mainly includes the square wave generation circuit, the high-frequency transformer and the three-terminal stabilized circuit. The first part is used to generate the 24V square wave, and as the input of the magnetic ring transformer. In the second part, the magnetic ring transformer consists of one input and three outputs to realize multi-channel isolation output. The third part can output different potential and realize non-equal potential function through the three-terminal stabilized chip. In addition, the multi-channel isolation power source proposed in this paper is Small size, high reliability and low price, and it is convenient for power electronic switches that operate on multiple different potentials. Therefore, the research on power supply of power electronic circuit has practical significance.

  11. Upgrading a marketing channels role

    Directory of Open Access Journals (Sweden)

    Tišma-Borota Ankica

    2002-01-01

    Full Text Available As one of the marketing mix instruments, marketing channels were usually behind other instruments (product, price and promotion. Many companies regarded marketing channels as something that was 'left' after more important strategies of price, product and promotion were created. In recent past, things have changed and marketing channels became more interesting for research. This change came as a result of change in global market functioning especially in competitive advantage, distributors' strength and increasing technology.

  12. Single-channel kinetics of BK (Slo1 channels

    Directory of Open Access Journals (Sweden)

    Yanyan eGeng

    2015-01-01

    Full Text Available Single-channel kinetics has proven a powerful tool to reveal information about the gating mechanisms that control the opening and closing of ion channels. This introductory review focuses on the gating of large conductance Ca2+- and voltage-activated K+ (BK or Slo1 channels at the single-channel level. It starts with single-channel current records and progresses to presentation and analysis of single-channel data and the development of gating mechanisms in terms of discrete state Markov (DSM models. The DSM models are formulated in terms of the tetrameric modular structure of BK channels, consisting of a central transmembrane pore-gate domain (PGD attached to four surrounding transmembrane voltage sensing domains (VSD and a large intracellular cytosolic domain (CTD, also referred to as the gating ring. The modular structure and data analysis shows that the Ca2+ and voltage dependent gating considered separately can each be approximated by 10-state two-tiered models with 5 closed states on the upper tier and 5 open states on the lower tier. The modular structure and joint Ca2+ and voltage dependent gating are consistent with a 50 state two-tiered model with 25 closed states on the upper tier and 25 open states on the lower tier. Adding an additional tier of brief closed (flicker states to the 10-state or 50-state models improved the description of the gating. For fixed experimental conditions a channel would gate in only a subset of the potential number of states. The detected number of states and the correlations between adjacent interval durations are consistent with the tiered models. The examined models can account for the single-channel kinetics and the bursting behavior of gating. Ca2+ and voltage activate BK channels by predominantly increasing the effective opening rate of the channel with a smaller decrease in the effective closing rate. Ca2+ and depolarization thus activate by mainly destabilizing the closed states.

  13. Nonnegative least-squares image deblurring: improved gradient projection approaches

    Science.gov (United States)

    Benvenuto, F.; Zanella, R.; Zanni, L.; Bertero, M.

    2010-02-01

    The least-squares approach to image deblurring leads to an ill-posed problem. The addition of the nonnegativity constraint, when appropriate, does not provide regularization, even if, as far as we know, a thorough investigation of the ill-posedness of the resulting constrained least-squares problem has still to be done. Iterative methods, converging to nonnegative least-squares solutions, have been proposed. Some of them have the 'semi-convergence' property, i.e. early stopping of the iteration provides 'regularized' solutions. In this paper we consider two of these methods: the projected Landweber (PL) method and the iterative image space reconstruction algorithm (ISRA). Even if they work well in many instances, they are not frequently used in practice because, in general, they require a large number of iterations before providing a sensible solution. Therefore, the main purpose of this paper is to refresh these methods by increasing their efficiency. Starting from the remark that PL and ISRA require only the computation of the gradient of the functional, we propose the application to these algorithms of special acceleration techniques that have been recently developed in the area of the gradient methods. In particular, we propose the application of efficient step-length selection rules and line-search strategies. Moreover, remarking that ISRA is a scaled gradient algorithm, we evaluate its behaviour in comparison with a recent scaled gradient projection (SGP) method for image deblurring. Numerical experiments demonstrate that the accelerated methods still exhibit the semi-convergence property, with a considerable gain both in the number of iterations and in the computational time; in particular, SGP appears definitely the most efficient one.

  14. UMTS Common Channel Sensitivity Analysis

    DEFF Research Database (Denmark)

    Pratas, Nuno; Rodrigues, António; Santos, Frederico

    2006-01-01

    and as such it is necessary that both channels be available across the cell radius. This requirement makes the choice of the transmission parameters a fundamental one. This paper presents a sensitivity analysis regarding the transmission parameters of two UMTS common channels: RACH and FACH. Optimization of these channels...... is performed and values for the key transmission parameters in both common channels are obtained. On RACH these parameters are the message to preamble offset, the initial SIR target and the preamble power step while on FACH it is the transmission power offset....

  15. Demystifying Mechanosensitive Piezo Ion Channels.

    Science.gov (United States)

    Xu, X Z Shawn

    2016-06-01

    Mechanosensitive channels mediate touch, hearing, proprioception, and blood pressure regulation. Piezo proteins, including Piezo1 and Piezo2, represent a new class of mechanosensitive channels that have been reported to play key roles in most, if not all, of these modalities. The structural architecture and molecular mechanisms by which Piezos act as mechanosensitive channels, however, remain mysterious. Two new studies have now provided critical insights into the atomic structure and molecular basis of the ion permeation and mechano-gating properties of the Piezo1 channel.

  16. Defect Distributions in Channeling Experiments

    DEFF Research Database (Denmark)

    Andersen, Hans Henrik; Sigmund, P.

    1965-01-01

    A simple collision model allows to calculate energy losses of perfectly channeled particles. The maximum energy loss is related in a simple way to the displacement energy of lattice atoms perpendicular to the channel. From that, one obtains rather definite predictions on the possibility...... of radiation damage by channeled particles. As an application, one gets a necessary criterion for the occurence of super tails in channeling experiments. The theory involves some assumptions on the behaviour of Born-Mayer potentials which are verified by comparison to experimental displacement energies....

  17. Quantum infinite square well with an oscillating wall

    International Nuclear Information System (INIS)

    Glasser, M.L.; Mateo, J.; Negro, J.; Nieto, L.M.

    2009-01-01

    A linear matrix equation is considered for determining the time dependent wave function for a particle in a one-dimensional infinite square well having one moving wall. By a truncation approximation, whose validity is checked in the exactly solvable case of a linearly contracting wall, we examine the cases of a simple harmonically oscillating wall and a non-harmonically oscillating wall for which the defining parameters can be varied. For the latter case, we examine in closer detail the dependence on the frequency changes, and we find three regimes: an adiabatic behabiour for low frequencies, a periodic one for high frequencies, and a chaotic behaviour for an intermediate range of frequencies.

  18. Identifying Dirac cones in carbon allotropes with square symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jinying [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Huang, Huaqing; Duan, Wenhui [Department of Physics, Tsinghua University, Beijing 100084 (China); Liu, Zhirong, E-mail: LiuZhiRong@pku.edu.cn [College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); State Key Laboratory for Structural Chemistry of Unstable and Stable Species and Beijing National Laboratory for Molecular Sciences (BNLMS), Peking University, Beijing 100871 (China)

    2013-11-14

    A theoretical study is conducted to search for Dirac cones in two-dimensional carbon allotropes with square symmetry. By enumerating the carbon atoms in a unit cell up to 12, an allotrope with octatomic rings is recognized to possess Dirac cones under a simple tight-binding approach. The obtained Dirac cones are accompanied by flat bands at the Fermi level, and the resulting massless Dirac-Weyl fermions are chiral particles with a pseudospin of S = 1, rather than the conventional S = 1/2 of graphene. The spin-1 Dirac cones are also predicted to exist in hexagonal graphene antidot lattices.

  19. Renormalization group theory of phase transitions in square Ising systems

    International Nuclear Information System (INIS)

    Nienhuis, B.

    1978-01-01

    Some renormalization group calculations are presented on a number of phase transitions in a square Ising model, both second and first order. Of these transitions critical exponents are calculated, the amplitudes of the power law divergences and the locus of the transition. In some cases attention is paid to the thermodynamic functions also far from the critical point. Universality and scaling are discussed and the renormalization group theory is reviewed. It is shown how a renormalization transformation, which relates two similar systems with different macroscopic dimensions, can be constructed, and how some critical properties of the system follow from this transformation. Several numerical and analytical applications are presented. (Auth.)

  20. Pattern formation in two-dimensional square-shoulder systems

    International Nuclear Information System (INIS)

    Fornleitner, Julia; Kahl, Gerhard

    2010-01-01

    Using a highly efficient and reliable optimization tool that is based on ideas of genetic algorithms, we have systematically studied the pattern formation of the two-dimensional square-shoulder system. An overwhelming wealth of complex ordered equilibrium structures emerge from this investigation as we vary the shoulder width. With increasing pressure three structural archetypes could be identified: cluster lattices, where clusters of particles occupy the sites of distorted hexagonal lattices, lane formation, and compact particle arrangements with high coordination numbers. The internal complexity of these structures increases with increasing shoulder width.

  1. Pattern formation in two-dimensional square-shoulder systems

    Energy Technology Data Exchange (ETDEWEB)

    Fornleitner, Julia [Institut fuer Festkoerperforschung, Forschungsszentrum Juelich, D-52425 Juelich (Germany); Kahl, Gerhard, E-mail: fornleitner@cmt.tuwien.ac.a [Institut fuer Theoretische Physik and Centre for Computational Materials Science (CMS), Technische Universitaet Wien, Wiedner Hauptstrasse 8-10, A-1040 Wien (Austria)

    2010-03-17

    Using a highly efficient and reliable optimization tool that is based on ideas of genetic algorithms, we have systematically studied the pattern formation of the two-dimensional square-shoulder system. An overwhelming wealth of complex ordered equilibrium structures emerge from this investigation as we vary the shoulder width. With increasing pressure three structural archetypes could be identified: cluster lattices, where clusters of particles occupy the sites of distorted hexagonal lattices, lane formation, and compact particle arrangements with high coordination numbers. The internal complexity of these structures increases with increasing shoulder width.

  2. Application of square-root filtering for spacecraft attitude control

    Science.gov (United States)

    Sorensen, J. A.; Schmidt, S. F.; Goka, T.

    1978-01-01

    Suitable digital algorithms are developed and tested for providing on-board precision attitude estimation and pointing control for potential use in the Landsat-D spacecraft. These algorithms provide pointing accuracy of better than 0.01 deg. To obtain necessary precision with efficient software, a six state-variable square-root Kalman filter combines two star tracker measurements to update attitude estimates obtained from processing three gyro outputs. The validity of the estimation and control algorithms are established, and the sensitivity of their performance to various error sources and software parameters are investigated by detailed digital simulation. Spacecraft computer memory, cycle time, and accuracy requirements are estimated.

  3. Handbook of Partial Least Squares Concepts, Methods and Applications

    CERN Document Server

    Vinzi, Vincenzo Esposito; Henseler, Jörg

    2010-01-01

    This handbook provides a comprehensive overview of Partial Least Squares (PLS) methods with specific reference to their use in marketing and with a discussion of the directions of current research and perspectives. It covers the broad area of PLS methods, from regression to structural equation modeling applications, software and interpretation of results. The handbook serves both as an introduction for those without prior knowledge of PLS and as a comprehensive reference for researchers and practitioners interested in the most recent advances in PLS methodology.

  4. Regularization Techniques for Linear Least-Squares Problems

    KAUST Repository

    Suliman, Mohamed

    2016-04-01

    Linear estimation is a fundamental branch of signal processing that deals with estimating the values of parameters from a corrupted measured data. Throughout the years, several optimization criteria have been used to achieve this task. The most astonishing attempt among theses is the linear least-squares. Although this criterion enjoyed a wide popularity in many areas due to its attractive properties, it appeared to suffer from some shortcomings. Alternative optimization criteria, as a result, have been proposed. These new criteria allowed, in one way or another, the incorporation of further prior information to the desired problem. Among theses alternative criteria is the regularized least-squares (RLS). In this thesis, we propose two new algorithms to find the regularization parameter for linear least-squares problems. In the constrained perturbation regularization algorithm (COPRA) for random matrices and COPRA for linear discrete ill-posed problems, an artificial perturbation matrix with a bounded norm is forced into the model matrix. This perturbation is introduced to enhance the singular value structure of the matrix. As a result, the new modified model is expected to provide a better stabilize substantial solution when used to estimate the original signal through minimizing the worst-case residual error function. Unlike many other regularization algorithms that go in search of minimizing the estimated data error, the two new proposed algorithms are developed mainly to select the artifcial perturbation bound and the regularization parameter in a way that approximately minimizes the mean-squared error (MSE) between the original signal and its estimate under various conditions. The first proposed COPRA method is developed mainly to estimate the regularization parameter when the measurement matrix is complex Gaussian, with centered unit variance (standard), and independent and identically distributed (i.i.d.) entries. Furthermore, the second proposed COPRA

  5. Positive Scattering Cross Sections using Constrained Least Squares

    International Nuclear Information System (INIS)

    Dahl, J.A.; Ganapol, B.D.; Morel, J.E.

    1999-01-01

    A method which creates a positive Legendre expansion from truncated Legendre cross section libraries is presented. The cross section moments of order two and greater are modified by a constrained least squares algorithm, subject to the constraints that the zeroth and first moments remain constant, and that the standard discrete ordinate scattering matrix is positive. A method using the maximum entropy representation of the cross section which reduces the error of these modified moments is also presented. These methods are implemented in PARTISN, and numerical results from a transport calculation using highly anisotropic scattering cross sections with the exponential discontinuous spatial scheme is presented

  6. Single Directional SMO Algorithm for Least Squares Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Xigao Shao

    2013-01-01

    Full Text Available Working set selection is a major step in decomposition methods for training least squares support vector machines (LS-SVMs. In this paper, a new technique for the selection of working set in sequential minimal optimization- (SMO- type decomposition methods is proposed. By the new method, we can select a single direction to achieve the convergence of the optimality condition. A simple asymptotic convergence proof for the new algorithm is given. Experimental comparisons demonstrate that the classification accuracy of the new method is not largely different from the existing methods, but the training speed is faster than existing ones.

  7. Square-lattice random Potts model: criticality and pitchfork bifurcation

    International Nuclear Information System (INIS)

    Costa, U.M.S.; Tsallis, C.

    1983-01-01

    Within a real space renormalization group framework based on self-dual clusters, the criticality of the quenched bond-mixed q-state Potts ferromagnet on square lattice is discussed. On qualitative grounds it is exhibited that the crossover from the pure fixed point to the random one occurs, while q increases, through a pitchfork bifurcation; the relationship with Harris criterion is analyzed. On quantitative grounds high precision numerical values are presented for the critical temperatures corresponding to various concentrations of the coupling constants J 1 and J 2 , and various ratios J 1 /J 2 . The pure, random and crossover critical exponents are discussed as well. (Author) [pt

  8. One-dimensional scattering problem for inverse square potential

    International Nuclear Information System (INIS)

    Mineev, V.S.

    1990-01-01

    Analytical continuation of the solution for the Schroedinger equation of inverse square potential, together with the modified method for variation of constants makes it possible to construct admittable self-adjoint extensions and to completely analyze the respective scattering problem along the entire line. In this case, the current density conservation and the wave function continuity when passing through the singular point x=0 require, that a 8-shaped induced potential should be introduced in the Schroedinger equation. The relevant calculations have shown that the potential x -2 can be either absolutely penetrable or absolutely impenetrable. 16 refs

  9. Optimization of sequential decisions by least squares Monte Carlo method

    DEFF Research Database (Denmark)

    Nishijima, Kazuyoshi; Anders, Annett

    change adaptation measures, and evacuation of people and assets in the face of an emerging natural hazard event. Focusing on the last example, an efficient solution scheme is proposed by Anders and Nishijima (2011). The proposed solution scheme takes basis in the least squares Monte Carlo method, which...... is proposed by Longstaff and Schwartz (2001) for pricing of American options. The present paper formulates the decision problem in a more general manner and explains how the solution scheme proposed by Anders and Nishijima (2011) is implemented for the optimization of the formulated decision problem...

  10. Regaining the Square of Opposition in Formal Ontology Development

    DEFF Research Database (Denmark)

    Nilsson, Jørgen Fischer

    2014-01-01

    be held simply in the case that "all P are Q" does not hold. These default rules are routinely adopted in ontology development without mentioning. Appealing to these conventions, the 4 sentence forms in the square are effectively made at disposal. We discuss a first order metalogical formalization...... of the 4 sentence forms with classes reified as individual constants elucidating the logical relationships between the sentence forms. Our formalization appeals to non-provability. Non-provability incurs non-monotonicity, implying that extension of an ontology with additional subclass relationships may...

  11. Angular Domain Data-Assisted Channel Estimation for Pilot Decontamination in Massive MIMO

    Directory of Open Access Journals (Sweden)

    Yihenew Beyene

    2017-01-01

    Full Text Available Massive Multiple-Input-Multiple-Output (M-MIMO system is a promising technology that offers to mobile networks substantial increase in throughput. In Time-Division Duplexing (TDD, the uplink training allows a Base Station (BS to acquire Channel State Information (CSI for both uplink reception and downlink transmission. This is essential for M-MIMO systems where downlink training pilots would consume large portion of the bandwidth. In densely populated areas, pilot symbols are reused among neighboring cells. Pilot contamination is the fundamental bottleneck on the performance of M-MIMO systems. Pilot contamination effect in antenna arrays can be mitigated by treating the channel estimation problem in angular domain where channel sparsity can be exploited. In this paper, we introduce a codebook that projects the channel into orthogonal beams and apply Minimum Mean-Squared Error (MMSE criterion to estimate the channel. We also propose data-aided channel covariance matrix estimation algorithm for angular domain MMSE channel estimator by exploiting properties of linear antenna array. The algorithm is based on simple linear operations and no matrix inversion is involved. Numerical results show that the algorithm performs well in mitigating pilot contamination where the desired channel and other interfering channels span overlapping angle-of-arrivals.

  12. 96-Channel receive-only head coil for 3 Tesla: design optimization and evaluation.

    Science.gov (United States)

    Wiggins, Graham C; Polimeni, Jonathan R; Potthast, Andreas; Schmitt, Melanie; Alagappan, Vijay; Wald, Lawrence L

    2009-09-01

    The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive-only phased-array head coil with 96 receive elements constructed on a close-fitting helmet-shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal-to-noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g-factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32-channel array built on an identical helmet-shaped former and to a larger commercial 12-channel head coil. The 96-channel coil provided substantial SNR gains in the distal cortex compared to the 12- and 32-channel coils. The central SNR for the 96-channel coil was similar to the 32-channel coil for optimum SNR combination and 20% lower for root-sum-of-squares combination. There was a significant reduction in the maximum g-factor for 96 channels compared to 32; for example, the 96-channel maximum g-factor was 65% of the 32-channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images.

  13. Preservation of meandering river channels in uniformly aggrading channel belts

    NARCIS (Netherlands)

    Lageweg, W.I. van de; Schuurman, F.; Cohen, K.M.; Dijk, W.M. van; Shimizu, Y.; Kleinhans, M.G.

    2016-01-01

    Channel belt deposits from meandering river systems commonly display an internal architecture of stacked depositional features with scoured basal contacts due to channel and bedform migration across a range of scales. Recognition and correct interpretation of these bounding surfaces is essential to

  14. MONETARY TRANSMISSION CHANNELS IN ROMANIA – THE CREDIT CHANNEL

    Directory of Open Access Journals (Sweden)

    Magdalena RĂDULESCU

    2009-12-01

    Full Text Available The theoretical – intuitive analysis applied to the segment of monetary transmission evidences the fact that forming the traditional monetary impulses transmission channels are in a starting phase due to the long financial non – intermediary process which Romanian economy had known. In these conditions, the exchange rate channel, and also NBR currency purchases was, for a long time, an important way through which monetary authorities actions influenced macro economical behaviors. But starting with 2000, it is observed a credit channel reactivation and, especially, interest rate channel. Anyhow, the credit channel continues to be undermined by the existence of liquidity surplus within the system, by the phenomena of substitution of national currency credit with currency credits, and also moral hazardous displays. Albeit some of these phenomena also affect the interest rate channel, its role in sending monetary policy impulses is in a continuous progress. Apparently, it acts by way of nominal interest rates, their real level seeming less relevant. Once with remaking the two traditional channels, the companies and households balance is configured and consolidated, which shall potentate in the future the efficiency of the monetary policy. This paper analyses the credit channel in Romania, through an unrestricted VAR analysis.. It shows the responses of exchange rate, inflation rate, GDP, interest rate, imports and exports to a shock on non-governmental credit

  15. ZnO-channel thin-film transistors: Channel mobility

    International Nuclear Information System (INIS)

    Hoffman, R.L.

    2004-01-01

    ZnO-channel thin-film transistor (TFT) test structures are fabricated using a bottom-gate structure on thermally oxidized Si; ZnO is deposited via RF sputtering from an oxide target, with an unheated substrate. Electrical characteristics are evaluated, with particular attention given to the extraction and interpretation of transistor channel mobility. ZnO-channel TFT mobility exhibits severe deviation from that assumed by ideal TFT models; mobility extraction methodology must accordingly be recast so as to provide useful insight into device operation. Two mobility metrics, μ avg and μ inc , are developed and proposed as relevant tools in the characterization of nonideal TFTs. These mobility metrics are employed to characterize the ZnO-channel TFTs reported herein; values for μ inc as high as 25 cm2/V s are measured, comprising a substantial increase in ZnO-channel TFT mobility as compared to previously reported performance for such devices

  16. Block Least Mean Squares Algorithm over Distributed Wireless Sensor Network

    Directory of Open Access Journals (Sweden)

    T. Panigrahi

    2012-01-01

    Full Text Available In a distributed parameter estimation problem, during each sampling instant, a typical sensor node communicates its estimate either by the diffusion algorithm or by the incremental algorithm. Both these conventional distributed algorithms involve significant communication overheads and, consequently, defeat the basic purpose of wireless sensor networks. In the present paper, we therefore propose two new distributed algorithms, namely, block diffusion least mean square (BDLMS and block incremental least mean square (BILMS by extending the concept of block adaptive filtering techniques to the distributed adaptation scenario. The performance analysis of the proposed BDLMS and BILMS algorithms has been carried out and found to have similar performances to those offered by conventional diffusion LMS and incremental LMS algorithms, respectively. The convergence analyses of the proposed algorithms obtained from the simulation study are also found to be in agreement with the theoretical analysis. The remarkable and interesting aspect of the proposed block-based algorithms is that their communication overheads per node and latencies are less than those of the conventional algorithms by a factor as high as the block size used in the algorithms.

  17. Quantitative determination of glycyrrhizinic acid by square-wave

    Directory of Open Access Journals (Sweden)

    Aneta Dimitrovska

    2003-06-01

    Full Text Available Novel adsorptive stripping square-wave voltammetric method as well as a new high-pressure liquid chromatographic method for direct determination of glycyrrhizinic acid in dosage pharmaceutical preparation, used against virus infections, have been developed. Glycyrrhizinic acid is an electrochemically active compound, which undergoes irreversible reduction on a mercury electrode surface in an aqueous medium. Its redox properties were studied thoroughly by means of square-wave voltammetry, as one of the most advanced electroanalytical technique. The voltammetric response depends mainly on the pH of the medium, composition of the supporting electrolyte, as well as the parameters of the excitement signal. It was also observed that the voltammetric properties strongly depend on the accumulation time and potential, revealing significant adsorption of glycyrrhizinic acid onto the mercury electrode surface. Upon this feature, an adsorptive stripping voltammetric method for quantitative determination of glycyrrhizinic acid was developed. A simple, sensitive and precise reversed phase HPLC method with photodiode array UV detection has also been developed, mainly for comparison and conformation of the results obtained with the voltammetric method.

  18. An Incremental Weighted Least Squares Approach to Surface Lights Fields

    Science.gov (United States)

    Coombe, Greg; Lastra, Anselmo

    An Image-Based Rendering (IBR) approach to appearance modelling enables the capture of a wide variety of real physical surfaces with complex reflectance behaviour. The challenges with this approach are handling the large amount of data, rendering the data efficiently, and previewing the model as it is being constructed. In this paper, we introduce the Incremental Weighted Least Squares approach to the representation and rendering of spatially and directionally varying illumination. Each surface patch consists of a set of Weighted Least Squares (WLS) node centers, which are low-degree polynomial representations of the anisotropic exitant radiance. During rendering, the representations are combined in a non-linear fashion to generate a full reconstruction of the exitant radiance. The rendering algorithm is fast, efficient, and implemented entirely on the GPU. The construction algorithm is incremental, which means that images are processed as they arrive instead of in the traditional batch fashion. This human-in-the-loop process enables the user to preview the model as it is being constructed and to adapt to over-sampling and under-sampling of the surface appearance.

  19. Between Community Spaces: Squares of Minor Centers of Calabria

    Directory of Open Access Journals (Sweden)

    Mauro Francini

    2017-08-01

    Full Text Available The theme of open “community spaces” in recent years has to the development of important interdisci­plinary issues. Nevertheless, the reading of smaller towns, in urbanistic, historical-anthropological and geographical terms appears less extended, considering the declination of public spaces as "squares." Starting from this declension we would like to introduce the first results of a research. The research had the aim of (reinterpreting the particular characteristics of these areas in specific areas such as small towns, using the region of Calabria for the case of analytic application. These communities have diverse and stratified living cultures, altered by settlement processes that have triggered two different types of urban contexts. The former often lead either to urban areas in depopulated decay or, in contrast, in places of memories: empty containers of relationships, sterile and crystallized museum objects, reduced to scenarios on which passing groups of visitors move necessarily from those realities. The latter often encircle primitive nuclei, asphyxiating them, or characterizing the so-called "dual" or "satellites" towns, completely detached from the original urban center in which all public functions are decentralized. The applied methodology is based on the reading of the historical-functional evolution of squares by the identification of codified compositional criteria. Through this research we seek to verify how urban planning, in synergy with other disciplines, can define processes of regeneration aimed at restoring the meaning of "center", and thus of an urban-community reference center.

  20. Square tracking sensor for autonomous helicopter hover stabilization

    Science.gov (United States)

    Oertel, Carl-Henrik

    1995-06-01

    Sensors for synthetic vision are needed to extend the mission profiles of helicopters. A special task for various applications is the autonomous position hold of a helicopter above a ground fixed or moving target. As a proof of concept for a general synthetic vision solution a restricted machine vision system, which is capable of locating and tracking a special target, was developed by the Institute of Flight Mechanics of Deutsche Forschungsanstalt fur Luft- und Raumfahrt e.V. (i.e., German Aerospace Research Establishment). This sensor, which is specialized to detect and track a square, was integrated in the fly-by-wire helicopter ATTHeS (i.e., Advanced Technology Testing Helicopter System). An existing model following controller for the forward flight condition was adapted for the hover and low speed requirements of the flight vehicle. The special target, a black square with a length of one meter, was mounted on top of a car. Flight tests demonstrated the automatic stabilization of the helicopter above the moving car by synthetic vision.

  1. Weighted least-squares criteria for electrical impedance tomography

    International Nuclear Information System (INIS)

    Kallman, J.S.; Berryman, J.G.

    1992-01-01

    Methods are developed for design of electrical impedance tomographic reconstruction algorithms with specified properties. Assuming a starting model with constant conductivity or some other specified background distribution, an algorithm with the following properties is found: (1) the optimum constant for the starting model is determined automatically; (2) the weighted least-squares error between the predicted and measured power dissipation data is as small as possible; (3) the variance of the reconstructed conductivity from the starting model is minimized; (4) potential distributions with the largest volume integral of gradient squared have the least influence on the reconstructed conductivity, and therefore distributions most likely to be corrupted by contact impedance effects are deemphasized; (5) cells that dissipate the most power during the current injection tests tend to deviate least from the background value. The resulting algorithm maps the reconstruction problem into a vector space where the contribution to the inversion from the background conductivity remains invariant, while the optimum contributions in orthogonal directions are found. For a starting model with nonconstant conductivity, the reconstruction algorithm has analogous properties

  2. Percolation of overlapping squares or cubes on a lattice

    International Nuclear Information System (INIS)

    Koza, Zbigniew; Kondrat, Grzegorz; Suszczyński, Karol

    2014-01-01

    Porous media are often modeled as systems of overlapping obstacles, which leads to the problem of two percolation thresholds in such systems, one for the porous matrix and the other for the void space. Here we investigate these percolation thresholds in the model of overlapping squares or cubes of linear size k > 1 randomly distributed on a regular lattice. We find that the percolation threshold of obstacles is a nonmonotonic function of k, whereas the percolation threshold of the void space is well approximated by a function linear in 1/k. We propose a generalization of the excluded volume approximation to discrete systems and use it to investigate the transition between continuous and discrete percolation, finding a remarkable agreement between the theory and numerical results. We argue that the continuous percolation threshold of aligned squares on a plane is the same for the solid and void phases and estimate the continuous percolation threshold of the void space around aligned cubes in a 3D space as 0.036(1). We also discuss the connection of the model to the standard site percolation with complex neighborhood. (paper)

  3. Plane-wave least-squares reverse-time migration

    KAUST Repository

    Dai, Wei

    2013-06-03

    A plane-wave least-squares reverse-time migration (LSRTM) is formulated with a new parameterization, where the migration image of each shot gather is updated separately and an ensemble of prestack images is produced along with common image gathers. The merits of plane-wave prestack LSRTM are the following: (1) plane-wave prestack LSRTM can sometimes offer stable convergence even when the migration velocity has bulk errors of up to 5%; (2) to significantly reduce computation cost, linear phase-shift encoding is applied to hundreds of shot gathers to produce dozens of plane waves. Unlike phase-shift encoding with random time shifts applied to each shot gather, plane-wave encoding can be effectively applied to data with a marine streamer geometry. (3) Plane-wave prestack LSRTM can provide higher-quality images than standard reverse-time migration. Numerical tests on the Marmousi2 model and a marine field data set are performed to illustrate the benefits of plane-wave LSRTM. Empirical results show that LSRTM in the plane-wave domain, compared to standard reversetime migration, produces images efficiently with fewer artifacts and better spatial resolution. Moreover, the prestack image ensemble accommodates more unknowns to makes it more robust than conventional least-squares migration in the presence of migration velocity errors. © 2013 Society of Exploration Geophysicists.

  4. Feature extraction through least squares fit to a simple model

    International Nuclear Information System (INIS)

    Demuth, H.B.

    1976-01-01

    The Oak Ridge National Laboratory (ORNL) presented the Los Alamos Scientific Laboratory (LASL) with 18 radiographs of fuel rod test bundles. The problem is to estimate the thickness of the gap between some cylindrical rods and a flat wall surface. The edges of the gaps are poorly defined due to finite source size, x-ray scatter, parallax, film grain noise, and other degrading effects. The radiographs were scanned and the scan-line data were averaged to reduce noise and to convert the problem to one dimension. A model of the ideal gap, convolved with an appropriate point-spread function, was fit to the averaged data with a least squares program; and the gap width was determined from the final fitted-model parameters. The least squares routine did converge and the gaps obtained are of reasonable size. The method is remarkably insensitive to noise. This report describes the problem, the techniques used to solve it, and the results and conclusions. Suggestions for future work are also given

  5. Making the most out of least-squares migration

    KAUST Repository

    Huang, Yunsong

    2014-09-01

    Standard migration images can suffer from (1) migration artifacts caused by an undersampled acquisition geometry, (2) poor resolution resulting from a limited recording aperture, (3) ringing artifacts caused by ripples in the source wavelet, and (4) weak amplitudes resulting from geometric spreading, attenuation, and defocusing. These problems can be remedied in part by least-squares migration (LSM), also known as linearized seismic inversion or migration deconvolution (MD), which aims to linearly invert seismic data for the reflectivity distribution. Given a sufficiently accurate migration velocity model, LSM can mitigate many of the above problems and can produce more resolved migration images, sometimes with more than twice the spatial resolution of standard migration. However, LSM faces two challenges: The computational cost can be an order of magnitude higher than that of standard migration, and the resulting image quality can fail to improve for migration velocity errors of about 5% or more. It is possible to obtain the most from least-squares migration by reducing the cost and velocity sensitivity of LSM.

  6. Making the most out of the least (squares migration)

    KAUST Repository

    Dutta, Gaurav

    2014-08-05

    Standard migration images can suffer from migration artifacts due to 1) poor source-receiver sampling, 2) weak amplitudes caused by geometric spreading, 3) attenuation, 4) defocusing, 5) poor resolution due to limited source-receiver aperture, and 6) ringiness caused by a ringy source wavelet. To partly remedy these problems, least-squares migration (LSM), also known as linearized seismic inversion or migration deconvolution (MD), proposes to linearly invert seismic data for the reflectivity distribution. If the migration velocity model is sufficiently accurate, then LSM can mitigate many of the above problems and lead to a more resolved migration image, sometimes with twice the spatial resolution. However, there are two problems with LSM: the cost can be an order of magnitude more than standard migration and the quality of the LSM image is no better than the standard image for velocity errors of 5% or more. We now show how to get the most from least-squares migration by reducing the cost and velocity sensitivity of LSM.

  7. Robust regularized least-squares beamforming approach to signal estimation

    KAUST Repository

    Suliman, Mohamed Abdalla Elhag

    2017-05-12

    In this paper, we address the problem of robust adaptive beamforming of signals received by a linear array. The challenge associated with the beamforming problem is twofold. Firstly, the process requires the inversion of the usually ill-conditioned covariance matrix of the received signals. Secondly, the steering vector pertaining to the direction of arrival of the signal of interest is not known precisely. To tackle these two challenges, the standard capon beamformer is manipulated to a form where the beamformer output is obtained as a scaled version of the inner product of two vectors. The two vectors are linearly related to the steering vector and the received signal snapshot, respectively. The linear operator, in both cases, is the square root of the covariance matrix. A regularized least-squares (RLS) approach is proposed to estimate these two vectors and to provide robustness without exploiting prior information. Simulation results show that the RLS beamformer using the proposed regularization algorithm outperforms state-of-the-art beamforming algorithms, as well as another RLS beamformers using a standard regularization approaches.

  8. BRGLM, Interactive Linear Regression Analysis by Least Square Fit

    International Nuclear Information System (INIS)

    Ringland, J.T.; Bohrer, R.E.; Sherman, M.E.

    1985-01-01

    1 - Description of program or function: BRGLM is an interactive program written to fit general linear regression models by least squares and to provide a variety of statistical diagnostic information about the fit. Stepwise and all-subsets regression can be carried out also. There are facilities for interactive data management (e.g. setting missing value flags, data transformations) and tools for constructing design matrices for the more commonly-used models such as factorials, cubic Splines, and auto-regressions. 2 - Method of solution: The least squares computations are based on the orthogonal (QR) decomposition of the design matrix obtained using the modified Gram-Schmidt algorithm. 3 - Restrictions on the complexity of the problem: The current release of BRGLM allows maxima of 1000 observations, 99 variables, and 3000 words of main memory workspace. For a problem with N observations and P variables, the number of words of main memory storage required is MAX(N*(P+6), N*P+P*P+3*N, and 3*P*P+6*N). Any linear model may be fit although the in-memory workspace will have to be increased for larger problems

  9. Dufour and Soret Effects on Square Porous Annulus

    Directory of Open Access Journals (Sweden)

    N. Nik-Ghazali

    2014-04-01

    Full Text Available A study on heat and mass transfer behaviour on porous medium embedded in a square annulus is conducted. The inner surface wall is considered to have a cool temperature Tc while the outer surface is exposed to a hot temperature Th. Finite element method (FEM is used to solve the governing partial differential equations. The results present the influences of the Dufour and Soret effects on the heat and mass transfer of a square annulus. The effects of various physical parameters on the temperature and concentration profiles together with the local Nusselt and Sherwood numbers are presented graphically. It is found that when Dufour parameter is increased, Nusselt number increases. Dufour effect has more influences on velocity profile, while it has no significant effect on the concentration and can be deemed negligible. It is observed that the local Nusselt number is highest at the bottom wall for low values of Dufour parameter; however, the top wall Nusselt number is highest for higher values of Dufour parameter. Soret effect tends to make more significant contribution to the concentration profile than Dufour effect.

  10. Thermodynamic properties of magnetic strings on a square lattice

    Science.gov (United States)

    Mol, Lucas; Oliveira, Denis Da Mata; Bachmann, Michael

    2015-03-01

    In the last years, spin ice systems have increasingly attracted attention by the scientific community, mainly due to the appearance of collective excitations that behave as magnetic monopole like particles. In these systems, geometrical frustration induces the appearance of degenerated ground states characterized by a local energy minimization rule, the ice rule. Violations of this rule were shown to behave like magnetic monopoles connected by a string of dipoles that carries the magnetic flux from one monopole to the other. In order to obtain a deeper knowledge about the behavior of these excitations we study the thermodynamics of a kind of magnetic polymer formed by a chain of magnetic dipoles in a square lattice. This system is expected to capture the main properties of monopole-string excitations in the artificial square spin ice. It has been found recently that in this geometry the monopoles are confined, but the effective string tension is reduced by entropic effects. To obtain the thermodynamic properties of the strings we have exactly enumerated all possible string configurations of a given length and used standard statistical mechanics analysis to calculate thermodynamic quantities. We show that the low-temperature behavior is governed by strings that satisfy ice rules. Financial support from FAPEMIG and CNPq (Brazilian agencies) are gratefully acknowledged.

  11. Efficient Model Selection for Sparse Least-Square SVMs

    Directory of Open Access Journals (Sweden)

    Xiao-Lei Xia

    2013-01-01

    Full Text Available The Forward Least-Squares Approximation (FLSA SVM is a newly-emerged Least-Square SVM (LS-SVM whose solution is extremely sparse. The algorithm uses the number of support vectors as the regularization parameter and ensures the linear independency of the support vectors which span the solution. This paper proposed a variant of the FLSA-SVM, namely, Reduced FLSA-SVM which is of reduced computational complexity and memory requirements. The strategy of “contexts inheritance” is introduced to improve the efficiency of tuning the regularization parameter for both the FLSA-SVM and the RFLSA-SVM algorithms. Experimental results on benchmark datasets showed that, compared to the SVM and a number of its variants, the RFLSA-SVM solutions contain a reduced number of support vectors, while maintaining competitive generalization abilities. With respect to the time cost for tuning of the regularize parameter, the RFLSA-SVM algorithm was empirically demonstrated fastest compared to FLSA-SVM, the LS-SVM, and the SVM algorithms.

  12. Flow past two tandem square cylinders vibrating transversely in phase

    International Nuclear Information System (INIS)

    Mithun, M G; Tiwari, Shaligram

    2014-01-01

    Numerical investigations have been carried out to study the wake characteristics of flow past two tandem square cylinders vibrating in phase. Both the cylinders vibrate in a transverse direction, i.e., perpendicular to the incoming flow with the same frequency and amplitude. The frequency of vibration of the cylinders and the inter-cylinder spacing are varied for fixed values of the Reynolds number (Re = 100) and the amplitude ratio (A/D = 0.4). The synchronous or lock-in regime for the oscillatory wake of the vibrating cylinders has been identified by varying the frequency of the vibration from f e  = 0.4 f 0 to 1.6 f 0 (f 0 being the frequency of vortex shedding behind a stationary square cylinder). The characteristics of lift and drag and the mechanism of vortex shedding are studied by varying the excitation frequency within the lock-in range for each value of inter-cylinder spacing. The complex interaction of flow between the cylinders gives rise to a variety of characteristically different shedding patterns in their wake. For values of inter-cylinder spacing equal to 2D and 3D, periodic, as well as quasi-periodic, lock-in behaviors are observed in the synchronous range. (paper)

  13. Improving the Ability of Mathematic Representation Capabilities and Students Skills in Importing Square Forms to Square Using Variation Solutions

    Science.gov (United States)

    Nirawati, R.

    2018-04-01

    This research was conducted to see whether the variation of the solution is acceptable and easy to understand by students with different level of ability so that it can be seen the difference of students ability in facilitating the quadratic form in the upper, middle and lower groups. This research used experimental method with factorial design. Based on the result of final test analysis, there were differences of students ability in upper group, medium group, and lower group in putting squared form based on the use certain variation of solution.

  14. Radioisotopic neutron transmission spectrometry: Quantitative analysis by using partial least-squares method

    International Nuclear Information System (INIS)

    Kim, Jong-Yun; Choi, Yong Suk; Park, Yong Joon; Jung, Sung-Hee

    2009-01-01

    Neutron spectrometry, based on the scattering of high energy fast neutrons from a radioisotope and slowing-down by the light hydrogen atoms, is a useful technique for non-destructive, quantitative measurement of hydrogen content because it has a large measuring volume, and is not affected by temperature, pressure, pH value and color. The most common choice for radioisotope neutron source is 252 Cf or 241 Am-Be. In this study, 252 Cf with a neutron flux of 6.3x10 6 n/s has been used as an attractive neutron source because of its high flux neutron and weak radioactivity. Pulse-height neutron spectra have been obtained by using in-house built radioisotopic neutron spectrometric system equipped with 3 He detector and multi-channel analyzer, including a neutron shield. As a preliminary study, polyethylene block (density of ∼0.947 g/cc and area of 40 cmx25 cm) was used for the determination of hydrogen content by using multivariate calibration models, depending on the thickness of the block. Compared with the results obtained from a simple linear calibration model, partial least-squares regression (PLSR) method offered a better performance in a quantitative data analysis. It also revealed that the PLSR method in a neutron spectrometric system can be promising in the real-time, online monitoring of the powder process to determine the content of any type of molecules containing hydrogen nuclei.

  15. Improved prediction of drug-target interactions using regularized least squares integrating with kernel fusion technique

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Ming; Wang, Yanli, E-mail: ywang@ncbi.nlm.nih.gov; Bryant, Stephen H., E-mail: bryant@ncbi.nlm.nih.gov

    2016-02-25

    Identification of drug-target interactions (DTI) is a central task in drug discovery processes. In this work, a simple but effective regularized least squares integrating with nonlinear kernel fusion (RLS-KF) algorithm is proposed to perform DTI predictions. Using benchmark DTI datasets, our proposed algorithm achieves the state-of-the-art results with area under precision–recall curve (AUPR) of 0.915, 0.925, 0.853 and 0.909 for enzymes, ion channels (IC), G protein-coupled receptors (GPCR) and nuclear receptors (NR) based on 10 fold cross-validation. The performance can further be improved by using a recalculated kernel matrix, especially for the small set of nuclear receptors with AUPR of 0.945. Importantly, most of the top ranked interaction predictions can be validated by experimental data reported in the literature, bioassay results in the PubChem BioAssay database, as well as other previous studies. Our analysis suggests that the proposed RLS-KF is helpful for studying DTI, drug repositioning as well as polypharmacology, and may help to accelerate drug discovery by identifying novel drug targets. - Graphical abstract: Flowchart of the proposed RLS-KF algorithm for drug-target interaction predictions. - Highlights: • A nonlinear kernel fusion algorithm is proposed to perform drug-target interaction predictions. • Performance can further be improved by using the recalculated kernel. • Top predictions can be validated by experimental data.

  16. Multi-frequency Phase Unwrap from Noisy Data: Adaptive Least Squares Approach

    Science.gov (United States)

    Katkovnik, Vladimir; Bioucas-Dias, José

    2010-04-01

    Multiple frequency interferometry is, basically, a phase acquisition strategy aimed at reducing or eliminating the ambiguity of the wrapped phase observations or, equivalently, reducing or eliminating the fringe ambiguity order. In multiple frequency interferometry, the phase measurements are acquired at different frequencies (or wavelengths) and recorded using the corresponding sensors (measurement channels). Assuming that the absolute phase to be reconstructed is piece-wise smooth, we use a nonparametric regression technique for the phase reconstruction. The nonparametric estimates are derived from a local least squares criterion, which, when applied to the multifrequency data, yields denoised (filtered) phase estimates with extended ambiguity (periodized), compared with the phase ambiguities inherent to each measurement frequency. The filtering algorithm is based on local polynomial (LPA) approximation for design of nonlinear filters (estimators) and adaptation of these filters to unknown smoothness of the spatially varying absolute phase [9]. For phase unwrapping, from filtered periodized data, we apply the recently introduced robust (in the sense of discontinuity preserving) PUMA unwrapping algorithm [1]. Simulations give evidence that the proposed algorithm yields state-of-the-art performance for continuous as well as for discontinues phase surfaces, enabling phase unwrapping in extraordinary difficult situations when all other algorithms fail.

  17. A library least-squares approach for scatter correction in gamma-ray tomography

    International Nuclear Information System (INIS)

    Meric, Ilker; Anton Johansen, Geir; Valgueiro Malta Moreira, Icaro

    2015-01-01

    Scattered radiation is known to lead to distortion in reconstructed images in Computed Tomography (CT). The effects of scattered radiation are especially more pronounced in non-scanning, multiple source systems which are preferred for flow imaging where the instantaneous density distribution of the flow components is of interest. In this work, a new method based on a library least-squares (LLS) approach is proposed as a means of estimating the scatter contribution and correcting for this. The validity of the proposed method is tested using the 85-channel industrial gamma-ray tomograph previously developed at the University of Bergen (UoB). The results presented here confirm that the LLS approach can effectively estimate the amounts of transmission and scatter components in any given detector in the UoB gamma-ray tomography system. - Highlights: • A LLS approach is proposed for scatter correction in gamma-ray tomography. • The validity of the LLS approach is tested through experiments. • Gain shift and pulse pile-up affect the accuracy of the LLS approach. • The LLS approach successfully estimates scatter profiles

  18. Improved prediction of drug-target interactions using regularized least squares integrating with kernel fusion technique

    International Nuclear Information System (INIS)

    Hao, Ming; Wang, Yanli; Bryant, Stephen H.

    2016-01-01

    Identification of drug-target interactions (DTI) is a central task in drug discovery processes. In this work, a simple but effective regularized least squares integrating with nonlinear kernel fusion (RLS-KF) algorithm is proposed to perform DTI predictions. Using benchmark DTI datasets, our proposed algorithm achieves the state-of-the-art results with area under precision–recall curve (AUPR) of 0.915, 0.925, 0.853 and 0.909 for enzymes, ion channels (IC), G protein-coupled receptors (GPCR) and nuclear receptors (NR) based on 10 fold cross-validation. The performance can further be improved by using a recalculated kernel matrix, especially for the small set of nuclear receptors with AUPR of 0.945. Importantly, most of the top ranked interaction predictions can be validated by experimental data reported in the literature, bioassay results in the PubChem BioAssay database, as well as other previous studies. Our analysis suggests that the proposed RLS-KF is helpful for studying DTI, drug repositioning as well as polypharmacology, and may help to accelerate drug discovery by identifying novel drug targets. - Graphical abstract: Flowchart of the proposed RLS-KF algorithm for drug-target interaction predictions. - Highlights: • A nonlinear kernel fusion algorithm is proposed to perform drug-target interaction predictions. • Performance can further be improved by using the recalculated kernel. • Top predictions can be validated by experimental data.

  19. Heat transfer to water at supercritical pressures in a circular and square annular flow geometry

    International Nuclear Information System (INIS)

    Licht, Jeremy; Anderson, Mark; Corradini, Michael

    2008-01-01

    A supercritical water heat transfer facility has been built at the University of Wisconsin to study heat transfer in a circular and square annular flow channel. Operating conditions included mass velocities of 350-1425 kg/m 2 s, heat fluxes up to 1.0 MW/m 2 , and bulk inlet temperatures up to 400 o C; all at a pressure of 25 MPa. The accuracy and validity of selected heat transfer correlations and buoyancy criterion were compared with heat transfer measurements. Jackson's Nusselt correlation was able to best predict the test data, capturing 86% of the data within 25%. Watts Nusselt correlation showed a similar trend but under predicted measurements by 10% relative to Jackson's. Comparison of experimental results with results of previous investigators has shown general agreement with high mass velocity data. Low mass velocity data have provided some insight into the difficulty in applying these Nusselt correlations to a region of deteriorated heat transfer. Geometrical differences in heat transfer were seen when deterioration was present. Jackson's buoyancy criterion predicted the onset of deterioration while modifications were applied to Seo's Froude number based criterion

  20. An improved channel assessment scheme

    KAUST Repository

    Bader, Ahmed

    2014-01-01

    A source node in a multihop network determines whether to transmit in a channel based on whether the channel is occupied by a packet transmission with a large number of relays; whether the source node is in the data tones back-off zone; and the source node is in the busy tone back-off zone.