Journal articles: 'Angle pairing'

1

Wang, Wei, and Xinle Shang. "The effect of the angle dependence of d-wave pairing gap on the asymmetric fermion superfluids." Modern Physics Letters B 29, no. 05 (February 20, 2015): 1550011. http://dx.doi.org/10.1142/s0217984915500116.

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A general analysis for the d-wave pairing in two components fermion system. Two physical conditions which can induce mismatched Fermi surfaces are considered: (i) Fixed chemical potential asymmetry δμ and (ii) fixed fermion number asymmetry α. In case (i), the gapless quasiparticle excitation arises both in usual Bardeen–Cooper–Schrieffer (BCS) and Sarma state due to the angle-dependent pairing gap, and they should be distinguished by gap susceptibility κΔ rather than the constraint Δ < δμ. Meanwhile, the d-wave pairing can hold larger chemical potential asymmetry δμ than the s-wave pairing. In case (ii), we find the angle dependence of the d-wave pairing gap can enhance the superfluidity for large asymmetry at low temperature.

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2

Jinli, C., G. Hong, and S. Weimin. "Angle estimation using ESPRIT without pairing in MIMO radar." Electronics Letters 44, no. 24 (2008): 1422. http://dx.doi.org/10.1049/el:20089089.

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Bok, Jin Mo, Jong Ju Bae, Han-Yong Choi, Chandra M. Varma, Wentao Zhang, Junfeng He, Yuxiao Zhang, Li Yu, and X. J. Zhou. "Quantitative determination of pairing interactions for high-temperature superconductivity in cuprates." Science Advances 2, no. 3 (March 2016): e1501329. http://dx.doi.org/10.1126/sciadv.1501329.

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A profound problem in modern condensed matter physics is discovering and understanding the nature of fluctuations and their coupling to fermions in cuprates, which lead to high-temperature superconductivity and the invariably associated strange metal state. We report the quantitative determination of normal and pairing self-energies, made possible by laser-based angle-resolved photoemission measurements of unprecedented accuracy and stability. Through a precise inversion procedure, both the effective interactions in the attractive d-wave symmetry and the repulsive part in the full symmetry are determined. The latter is nearly angle-independent. Near Tc, both interactions are nearly independent of frequency and have almost the same magnitude over the complete energy range of up to about 0.4 eV, except for a low-energy feature at around 50 meV that is present only in the repulsive part, which has less than 10% of the total spectral weight. Well below Tc, they both change similarly, with superconductivity-induced features at low energies. Besides finding the pairing self-energy and the attractive interactions for the first time, these results expose the central paradox of the problem of high Tc: how the same frequency-independent fluctuations can dominantly scatter at angles ±π/2 in the attractive channel to give d-wave pairing and lead to angle-independent repulsive scattering. The experimental results are compared with available theoretical calculations based on antiferromagnetic fluctuations, the Hubbard model, and quantum-critical fluctuations of the loop-current order.

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Zhang, Lufeng, Tongyun Huang, Ying Liang, and Tianxing Ma. "Ground state superconducting pair correlations in twisted bilayer graphene." Modern Physics Letters B 34, no. 01 (December 18, 2019): 2050016. http://dx.doi.org/10.1142/s0217984920500165.

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Motivated by the recent novel electronic features extracted from the magic-angle graphene superlattices, we studied the ground state superconducting pairing correlations within the Hubbard model on a twisted bilayer honeycomb lattice. Using Constrained-Path Quantum Monte Carlo method, we found that the [Formula: see text] pairing correlation dominates over other pairing patterns among various electron fillings and interaction strengths, and the effective pairing interaction was enhanced as the on-site Coulomb interaction increased. We further examined the effect of the nearest neighbor interaction [Formula: see text], and the effective pairing interaction with [Formula: see text] pairing symmetry was also enhanced by either a repulsive or attractive interaction. Our intensive numerical results confirm the interaction driven superconductivity with a dominant [Formula: see text] pairing symmetry in twisted bilayer graphene.

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5

Xudong, Wang, Xiaofei Zhang, Jianfeng Li, and Jinchao Bai. "Improved ESPRIT Method for Joint Direction-of-Arrival and Frequency Estimation Using Multiple-Delay Output." International Journal of Antennas and Propagation 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/309269.

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An automatic pairing joint direction-of-arrival (DOA) and frequency estimation is presented to overcome the unsatisfactory performances of estimation of signal parameter via rotational invariance techniques- (ESPRIT-) like algorithm of Wang (2010), which requires an additional pairing. By using multiple-delay output of a uniform linear antenna arrays (ULA), the proposed algorithm can estimate joint angles and frequencies with an improved ESPRIT. Compared with Wang’s ESPRIT algorithm, the angle estimation performance of the proposed algorithm is greatly improved. The frequency estimation performance of the proposed algorithm is same with that of Wang’s ESPRIT algorithm. Furthermore, the proposed algorithm can obtain automatic pairing DOA and frequency parameters, and it has a comparative computational complexity in contrast to Wang’s ESPRIT algorithm. By the way, this proposed algorithm can also work well for nonuniform linear arrays. The useful behavior of this proposed algorithm is verified by simulations.

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6

Chen, Shihong, Qingchang Tao, Zhongtian Yang, Xudong Wang, Sijia Liu, and Wei Xu. "Joint Angle and Frequency Estimation in Linear Arrays Based on Covariance Reconstruction and ESPRIT." Mathematical Problems in Engineering 2021 (July 8, 2021): 1–15. http://dx.doi.org/10.1155/2021/5477848.

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Joint angle and frequency estimation, one of the key technologies in wireless communication and radar science, has been extensively studied by scholars. For linear arrays, this paper proposes a joint angle and frequency estimation method based on covariance reconstruction and the estimation of signal parameters via rotational invariance techniques (CR-ESPRIT). We first use the received conjugate signal to reconstruct a covariance matrix. Then, we use the least squares-ESPRIT (LS-ESPRIT) algorithm to estimate the desired frequencies. Finally, we estimate the angles according to the reconstructed matrix. The proposed method can estimate signal parameters via automatic pairing and without an additional parameter pairing process under the condition of a uniform or a nonuniform array. Moreover, this method has high estimation accuracy, excellent and stable anti-noise performance, and strong algorithmic robustness. Through a computer simulation analysis, we can confirm the reliability and validity of the proposed parameter estimation method. A comparison with other methods further proves the performance advantages of the developed method. The method in this paper can be easily applied to many signal processing contexts, such as electronic reconnaissance and wireless communication.

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POMORSKI, KRZYSZTOF. "PAIRING AS A COLLECTIVE MODE." International Journal of Modern Physics E 16, no. 02 (February 2007): 237–48. http://dx.doi.org/10.1142/s0218301307005685.

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The collective pairing hamiltonian is obtained in the framework of the generator coordinate method using the Gaussian overlap approximation. A slightly modified BCS wave function is used as a generator function. The pairing gap parameter Δ and the gauge transformation angle ϕ are chosen as generator coordinates. This model gives not only an approximate particle-number projection but also the form of the ground state collective wave function in the (Δ, ϕ) plane. It was found that the most probable Δ does not corresponds to the minimum (Δ eq ) of the energy function E BCS (Δ) but it is systematically shifted towards smaller values than Δ eq . This effect is due to the strong dependence of the mass parameters on the pairing gap. The influence of the dynamics in the pairing degrees of freedom on the fission life-times as well as the quadrupole collective excitations is examined.

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8

Choi, Han-Yong, and Jin Mo Bok. "How to pin down the pairing interaction for high Tc superconductivity in cuprates." International Journal of Modern Physics B 32, no. 17 (July 9, 2018): 1840026. http://dx.doi.org/10.1142/s021797921840026x.

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The normal and pairing self-energies are the microscopic quantities which reflect and characterize the underlying interaction in superconductors. The momentum and frequency dependence of the self-energies, therefore, provides the experimental criteria which can single out the long sought-after pairing interaction among many proposed ideas. This line of research to pin down the pairing interaction for the cuprate superconductors has been carried out with some success by analyzing the momentum distribution curves (MDCs) of laser angle-resolved photo-emission spectroscopy (ARPES) data. Some progress and results are presented and compared with theoretical calculations based on leading proposals. Comments are made on the proposed scenarios from the comparisons.

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Yan, Yanjun, Huihui Xu, Ning Zhang, Guangjie Han, and Mingliu Liu. "Dynamic Divide Grouping Non-Orthogonal Multiple Access in Terrestrial-Satellite Integrated Network." Sensors 21, no. 18 (September 16, 2021): 6199. http://dx.doi.org/10.3390/s21186199.

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Non-orthogonal multiple access (NOMA) has been extensively studied to improve the performance of the Terrestrial-Satellite Integrated Network (TSIN) on account of the shortage of frequency band resources. In this paper, the terrestrial network and satellite network synergistically provide complete coverage for ground users, and based on the architecture, we first formulate a constrained optimization problem to maximize the sum rate of the TSIN under the limited spectrum resources. As the terrestrial networks and the satellite network will cause interference to each other, we first investigate the capacity performance of the terrestrial networks and the satellite networks separately, in which the optimal power control factor expression is derived. Then, by constructing the relationship model between user elevation angle, beam angle and distance, we develop a dynamic group pairing schemes to ensure the effective pairing of NOMA users. Based on the user pairing, to obtain the optimal resource allocation, a joint optimization algorithm of power allocation, beam channel and base station channel resource is proposed. Finally, simulation results are provided to evaluate the user paring scheme as well as the total system performance, in comparison with the existing works.

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10

Brandstätter, G., H. W. Weber, T. Chattopadhyay, R. Cubitt, H. Fischer, M. Wylie, G. A. Emel'chenko, and A. Wiedenmann. "Neutron Diffraction by the Flux Line Lattice in YBa2Cu3O7−δ Single Crystals." Journal of Applied Crystallography 30, no. 5 (October 1, 1997): 571–74. http://dx.doi.org/10.1107/s0021889897001854.

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Small-angle neutron diffraction was used to image the mixed state in a large superconducting YBa2Cu3O7−δ single crystal. The flux line lattice was observed in fields up to 2 T at various temperatures from 2.4 to 80 K. The integrated intensity I of the (10) reflection was calculated as a function of temperature for three different fields (0.8, 1 and 2 T). From these I(T) curves, the magnetic penetration depth λ(T) was obtained on an absolute scale. This quantity is of particular interest, since it provides information on the nature of the pairing mechanism in the superconductor, i.e. the symmetry of the wavefunction of the electron pairs. The results are discussed in terms of BCS theory (s-wave pairing) and of d-wave pairing with and without impurity scattering.

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11

ZHANG, XIAOFEI, CHEN CHEN, YINGJIE HUANG, HAILANG WU, JIANFENG LI, and DAZHUAN XU. "BLIND JOINT ANGLE, FREQUENCY AND POLARIZATION ESTIMATION FOR POLARIZATION SENSITIVE ARRAY USING QUADRILINEAR DECOMPOSITION." Journal of Circuits, Systems and Computers 22, no. 02 (February 2013): 1250091. http://dx.doi.org/10.1142/s0218126612500910.

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This paper links the polarization-sensitive-array parameter estimation problem to the quadrilinear model. Exploiting this link, it derives a blind joint angle, frequency and polarization estimation algorithm. The simulation results reveal that the proposed algorithm has better angle, frequency and polarization estimation performance than ESPRIT. This algorithm relies on a fundamental result of the uniqueness of low-rank four-way data decomposition. Furthermore, the proposed algorithm does not require pairing among multiple parameters. Simulation results illustrate performance of this algorithm.

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12

CHEN, WEIYANG, and XIAOFEI ZHANG. "IMPROVED SPECTRUM SEARCHING GENERALIZED–ESPRIT ALGORITHM FOR JOINT DOD AND DOA ESTIMATION IN MIMO RADAR WITH NON-UNIFORM LINEAR ARRAYS." Journal of Circuits, Systems and Computers 23, no. 08 (June 18, 2014): 1450106. http://dx.doi.org/10.1142/s0218126614501060.

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This paper investigates the problem of angle estimation for bistatic multiple-input multiple-output (MIMO) radar with non-uniform linear arrays, and proposes an improved spectrum searching generalized estimation of signal parameters via rotational invariance techniques (ESPRIT) algorithm for joint direction of departure (DOD) and direction of arrival (DOA) estimation algorithm in bistatic MIMO radar. The proposed algorithm obtains initial estimation of angles obtained from the signal subspace, and uses the 1D local searchings to achieve the joint estimation of DOD and DOA. Compared to the spectrum searching generalized-ESPRIT algorithm which requires the global searchings and additional pairing, the proposed algorithm just needs the local searchings and obtains automatically paired 2D angle estimation. The angle estimation performance of the proposed algorithm is almost the same as that of the generalized-ESPRIT algorithm, and better than ESPRIT-like algorithm. Furthermore, the proposed algorithm is suitable for irregular array geometry, has much lower complexity than the spectrum searching generalized-ESPRIT algorithm, and imposes less constraint on the transmit/receive sensor spacing, which need not be limited to a half-wavelength strictly. The simulation results verify the effectiveness of the algorithm.

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13

Zhang, Juan, Hongbao Fan, Chenhong Wang, Linrang Zhang, and Shiyang Tang. "Distance estimation and pairing for low angle group targets based on radar time reversal." Digital Signal Processing 106 (November 2020): 102808. http://dx.doi.org/10.1016/j.dsp.2020.102808.

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14

Qiu, Xiao Feng, and Xiao Fei Zhang. "Interference Localization via Direction of Arrival Estimation for Satellite with Planar Array." Advanced Materials Research 1049-1050 (October 2014): 1788–91. http://dx.doi.org/10.4028/www.scientific.net/amr.1049-1050.1788.

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This paper presents the model of satellite planar array, and interference localization via direction of arrival (DOA) estimation. We derive a dimension reduction DOA estimaton algorithm therein. The proposed algorithm, which only requires a one-dimensional local searching, can avoid the high computational cost within two-dimensional multiple signal classification (2D-MUSIC) algorithm. We illustrate that the proposed algorithm has better angle estimation performance than estimation method of signal parameters via rotational invariance technique (ESPRIT) algorithm, and has very close angle estimation performance to 2D-MUSIC algorithm. Furthermore, our algorithm requires no extra pairing. Simulation results present the usefulness of our algorithm.

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15

Wang, Jun, Hong Xiang, Shaoming Wei, and Zhongsheng Sun. "Estimating Direction of Arrival by Using Two-Dimensional State-Space Balance Method." International Journal of Antennas and Propagation 2017 (2017): 1–5. http://dx.doi.org/10.1155/2017/4890203.

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A study of a two-dimensional state-space balance (2D SSB) method for estimating direction of arrival (DOA) for uniform rectangular array (URA) is presented in this letter. The comprehensive utilization of controllability and observability matrices and automatic pairing technique are considered in this method by using the single snapshot. Therefore, the DOAs of elevation angle and azimuth angle can pair automatically and acquire better estimation performance compared with 2D matrix pencil method or unitary matrix pencil method. In addition, the proposed method can handle correlated signals directly without preprocessing. Simulation is conducted to verify the effectiveness of the proposed method.

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16

Semenov, A. V. "The Simple Generalized BCS-Type Model for the Acoustic Plasmon Induced d-Wave Superconductivity in High-Tc Layered Cuprate Compounds." International Journal of Modern Physics B 12, no. 29n31 (December 20, 1998): 3141–45. http://dx.doi.org/10.1142/s0217979298002234.

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A simple analytically treated model is presented for high-T c superconductivity in layered cuprate compounds. This model assumes a cylindrical Fermi-surface with circular cross-section, but anisotropic Fermi-velocity (density of states), which is approximated by a step-like function on azimuth angle. The system under these assumptions is shown to support in the long wavelength limit collective charge-density excitations with acoustic spectrum (acoustic plasmons), which suppress the Coulomb interelectron repulsion for small transferred momenta. This result leads to the second essential feature of the proposed model: besides the standard assumptions of the BCS scheme the effective potential of interelectron interaction is characterized by additional step-like dependence on the absolute value of two-dimensional transferred quasimomenta. The effective constants of the Cooper pairing in anisotropic s- and d-wave channels are evaluated. It is shown, that the plasmon mechanism gives rise to the pairing in the d-wave channel despite the fully isotropic (in two dimensions) model potential. The Umklapp processes are taken into account and are shown to increase the pairing constants.

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17

Nazarova, Elena, Eileen O'Toole, Susi Kaitna, Paul Francois, Mark Winey, and Jackie Vogel. "Distinct roles for antiparallel microtubule pairing and overlap during early spindle assembly." Molecular Biology of the Cell 24, no. 20 (October 15, 2013): 3238–50. http://dx.doi.org/10.1091/mbc.e13-05-0232.

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During spindle assembly, microtubules may attach to kinetochores or pair to form antiparallel pairs or interpolar microtubules, which span the two spindle poles and contribute to mitotic pole separation and chromosome segregation. Events in the specification of the interpolar microtubules are poorly understood. Using three-dimensional electron tomography and analysis of spindle dynamical behavior in living cells, we investigated the process of spindle assembly. Unexpectedly, we found that the phosphorylation state of an evolutionarily conserved Cdk1 site (S360) in γ-tubulin is correlated with the number and organization of interpolar microtubules. Mimicking S360 phosphorylation (S360D) results in bipolar spindles with a normal number of microtubules but lacking interpolar microtubules. Inhibiting S360 phosphorylation (S360A) results in spindles with interpolar microtubules and high-angle, antiparallel microtubule pairs. The latter are also detected in wild-type spindles <1 μm in length, suggesting that high-angle microtubule pairing represents an intermediate step in interpolar microtubule formation. Correlation of spindle architecture with dynamical behavior suggests that microtubule pairing is sufficient to separate the spindle poles, whereas interpolar microtubules maintain the velocity of pole displacement during early spindle assembly. Our findings suggest that the number of interpolar microtubules formed during spindle assembly is controlled in part through activities at the spindle poles.

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Kamashev, Andrey, Aidar Validov, Nadir Garif’yanov, Yakov Fominov, Pavel Leksin, Joachim Schumann, Jürgen Thomas, Vladislav Kataev, Bernd Büchner, and Ilgiz Garifullin. "Isolation of proximity-induced triplet pairing channel in a superconductor/ferromagnet spin valve." EPJ Web of Conferences 185 (2018): 08001. http://dx.doi.org/10.1051/epjconf/201818508001.

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In the present work we have studied the proximity-induced superconducting triplet pairing in CoOx/Py1/Cu/Py2/Cu/Pb spin-valve structure (where Py = Ni0:81Fe0:19). For CoOx(3 nm)/Py(3 nm)/Cu(4 nm)/Py(0.6 nm)/Cu(2 nm)/Pb(70 nm) we have studied the dependence of the Tc on the angle α between the direction of the cooling field and the external field both applied in the plane of the sample. We obtained that the Tc does not change monotonically with the angle but passes through a minimum. To observe an “isolated” triplet spin-valve effect we exploited the oscillatory feature of the magnitude of the ordinary spin-valve effect ΔTc in the dependence of the Py2-layer thickness dPy2. We determined the value of dPy2 at which ΔTc caused by the ordinary spin-valve effect is suppressed. This means that the difference in the Tc between the antiparallel and parallel mutual orientation of magnetizations of the Py1 and Py2 layers is zero. For such a sample a “pure” triplet spin-valve effect which causes the minimum in Tc at the orthogonal configuration of magnetizations has been observed.

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MISHONOV, T. M., J. P. WALLINGTON, E. S. PENEV, and J. O. INDEKEU. "REDUCED PAIRING HAMILTONIAN FOR INTERATOMIC TWO-ELECTRON EXCHANGE IN LAYERED CUPRATES." Modern Physics Letters B 16, no. 19 (August 20, 2002): 693–99. http://dx.doi.org/10.1142/s0217984902004160.

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A detailed Linear Combination of Atomic Orbitals (LCAO) tight-binding model is developed for the layered High-Temperature Superconductor (HTSC) cuprates. The band structure of these materials is described using a σ-band Hamiltonian employing Cu 4s, Cu 3dx2 - y2, O 2px and O 2py atomic orbitals. The Fermi level and the shape of the resulting Fermi surface are fitted to recent Angle Resolved Photon Emission Spectroscopy (ARPES) data to realistically determine the dispersion in the conduction band. Electron-electron interactions and, ultimately, Cooper pairing are obtained by introducing a Heitler–London, two-electron exchange between adjacent orbitals within the CuO 2 plane. Finally, using the LCAO wavefunctions determined by the band structure fit, the Bardeen–Cooper–Schrieffer (BCS) type kernel is derived for interatomic exchange.

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20

Chatake, Toshiyuki, Tomoko Sunami, Akira Ono, Yoshihito Ueno, Akira Matsuda, and Akio Takenaka. "Crystallization and preliminary analysis of a DNA dodecamer of d(CGCGmo6AATCCGCG) containing 2′-deoxy-N 6-methoxyadenosine: change in crystal packing with different humidity." Acta Crystallographica Section D Biological Crystallography 55, no. 4 (April 1, 1999): 873–76. http://dx.doi.org/10.1107/s0907444998014048.

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The DNA dodecamer of (CGCGmo6AATCCGCG) containing 2′-deoxy-N 6-methoxyadenosine has been crystallized for X-ray analysis in order to investigate the effects of the modified adenosine on base pairing. It has been found that the crystal changes from one form to another during data collection in a manner similar to a phase transition. The two crystal structures show that this phenomenon, ascribed to differences in humidity, is correlated with a change in the contact angle between the two duplexes.

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Eskildsen, M. R., E. M. Forgan, and H. Kawano-Furukawa. "Vortex structures, penetration depth and pairing in iron-based superconductors studied by small-angle neutron scattering." Reports on Progress in Physics 74, no. 12 (September 19, 2011): 124504. http://dx.doi.org/10.1088/0034-4885/74/12/124504.

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22

Nakayama, Kosuke, Koshin Shigekawa, Katsuaki Sugawara, Takashi Takahashi, and Takafumi Sato. "Unusual Temperature Evolution of Quasiparticle Band Dispersion in Electron-Doped FeSe Films." Symmetry 13, no. 2 (January 20, 2021): 155. http://dx.doi.org/10.3390/sym13020155.

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The discovery of high-temperature (high-Tc) superconductivity in one-monolayer FeSe on SrTiO3 has attracted tremendous attention. Subsequent studies suggested the importance of cooperation between intra-FeSe-layer and interfacial interactions to enhance Tc. However, the nature of intra-FeSe-layer interactions, which would play a primary role in determining the pairing symmetry, remains unclear. Here we have performed high-resolution angle-resolved photoemission spectroscopy of one-monolayer and alkaline-metal-deposited multilayer FeSe films on SrTiO3, and determined the evolution of quasiparticle band dispersion across Tc. We found that the band dispersion in the superconducting state deviates from the Bogoliubov-quasiparticle dispersion expected from the normal-state band dispersion with a constant gap size. This suggests highly anisotropic pairing originating from small momentum transfer and/or mass renormalization due to electron–boson coupling. This band anomaly is interpreted in terms of the electronic interactions within the FeSe layers that may be related to the high-Tc superconductivity in electron-doped FeSe.

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Gu, Jian-Feng, and Ping Wei. "Joint SVD of Two Cross-Correlation Matrices to Achieve Automatic Pairing in 2-D Angle Estimation Problems." IEEE Antennas and Wireless Propagation Letters 6 (2007): 553–56. http://dx.doi.org/10.1109/lawp.2007.907913.

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Kong, Bo, Yuhao Wang, Xiaohua Deng, and Dong Qin. "Joint Range-Doppler-Angle Estimation for OFDM-Based RadCom System via Tensor Decomposition." Wireless Communications and Mobile Computing 2018 (August 1, 2018): 1–12. http://dx.doi.org/10.1155/2018/2708416.

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Radar and communication (RadCom) systems have received increasing attention due to their high energy efficiency and spectral efficiency. They have been identified as green communications. This paper is concerned with a joint estimation of range-Doppler-angle parameters for an orthogonal frequency division multiplexing (OFDM) based RadCom system. The key idea of the proposed method is to derive different factor matrices by the tensor decomposition method and then extract parameters of the targets from these factor matrices. Different from the classical tensor decomposition method via alternating least squares or higher-order singular value decomposition, we adopt a greedy based method with each step constituted by a rank-1 approximation subproblem. To avoid local extremum, the rank-1 approximation is solved by using a multiple random initialized tensor power method with a comparison procedure followed. A parameterized rectification method is also proposed to incorporate the inherent structures of the factor matrices. The proposed algorithm can estimate all the parameters simultaneously without parameter pairing requirement. The numerical experiments demonstrate superior performance of the proposed algorithm compared with the existing methods.

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Gao, Xiaofeng, Xinhong Hao, Ping Li, and Guolin Li. "An Improved Two-Dimensional Direction-Of-Arrival Estimation Algorithm for L-Shaped Nested Arrays with Small Sample Sizes." Sensors 19, no. 9 (May 10, 2019): 2176. http://dx.doi.org/10.3390/s19092176.

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In this paper, an improved two-dimensional (2-D) direction of arrival (DOA) estimation algorithm for L-shaped nested arrays is proposed. Unlike the approach for a classical nested array, which use the auto-correlation matrix (ACM) to increase the degrees of freedom (DOF), we utilize the cross-correlation matrix (CCM) of different sub-arrays to generate two long consecutive virtual arrays. These acquire a large number of DOF without redundant elements and eliminate noise effects. Furthermore, we reconstruct the CCM based on the singular value decomposition (SVD) operation in order to reduce the perturbation of noise for small numbers of samples. To cope with the matrix rank deficiency of the virtual arrays, we construct the full rank equivalent covariance matrices by using the output and its conjugate vector of virtual arrays. The unitary estimation of signal parameters via rotational invariance technique (ESPRIT) is then performed on the covariance matrices to obtain the DOA of incident signals with low computational complexity. Finally, angle pairing is achieved by deriving the equivalent signal vector of the virtual arrays using the estimated angles. Numerical simulation results show that the proposed algorithm not only provides more accurate 2-D DOA estimation performance with low complexity, but also achieves angle estimation for small numbers of samples compared to existing similar methods.

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Guo, Chenxi, Xinhong Hao, and Ping Li. "An Improved Trilinear Model-Based Angle Estimation Method for Co-Prime Planar Arrays." Sensors 18, no. 12 (November 28, 2018): 4180. http://dx.doi.org/10.3390/s18124180.

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Angle estimation methods in two-dimensional co-prime planar arrays have been discussed mainly based on peak searching and sparse recovery. Peak searching methods suffer from heavy computational complexity and sparse recovery methods face some problems in selecting the regularization parameters. In this paper, we propose an improved trilinear model-based method for angle estimation for co-prime planar arrays in the view of trilinear decomposition, namely parallel factor analysis. Due to the principle of trilinear decomposition, our method does not require peak searching and can conduct auto-pairing easily, which can reduce the computational loads and avoid parameter selection problems. Furthermore, we exploit the virtual array concept of the whole co-prime planar array through the cross-correlation matrix obtained from the received signal data and present a matrix reconstruction method using the Khatri–Rao product to tackle the matrix rank deficiency problem in the virtual array condition. The simulation results show that our proposed method can not only achieve high estimation accuracy with low complexity compared to other similar approaches, but also utilize limited sensor number to implement the angle estimation tasks.

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Zhang, Lei, Ying-Long Ge, Xin-Le Shang, and Yuan Gao. "New orientations of the Cooper pair momentum in FFLO state for asymmetric D-wave fermion superfluids." Modern Physics Letters B 33, no. 07 (March 10, 2019): 1950082. http://dx.doi.org/10.1142/s0217984919500829.

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The Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) state in asymmetric D-wave fermion superfluids is investigated generally. The angle dependence of the pairing gap (angle-dependent gap) for D-wave is also considered. Except the two special orientations of the Cooper pair momentum which are parallel/orthogonal to the symmetry-axis of ADG (called as FFLO-ADG-O and FFLO-ADG-P states), new orientations of the Cooper pair momentum between the two special ones are also found. These new orientations of the Cooper pair momentum correspond to new possible locally stable state (defined as FFLO-ADG-B state). Furthermore, the FFLO-ADG-O state is favored for small asymmetry and the FFLO-ADG-P state is located at large asymmetry, whereas the FFLO-ADG-B state is stable for moderate asymmetry. Moreover, the range of the asymmetry where the superfluids exists is enhanced strongly by taking the ADG to the FFLO state.

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Hong, Seung Hwan, and Han-Yong Choi. "Angle and frequency dependence of self-energy from spin fluctuation mediated d-wave pairing for high temperature superconductors." Journal of Physics: Condensed Matter 25, no. 36 (August 9, 2013): 365702. http://dx.doi.org/10.1088/0953-8984/25/36/365702.

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McKeown, Neil B., Hong Li, and Madeleine Helliwell. "A non-planar, hexadeca-substituted, metal-free phthalocyanine." Journal of Porphyrins and Phthalocyanines 09, no. 12 (December 2005): 841–45. http://dx.doi.org/10.1142/s1088424605000964.

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The readily prepared 2,3,9,10,16,17,23,24-octamethyl-1,4,8,11,15,18,22,25-octaoctyloxyphthalocyanine (Pc 1) adopts a non-planar conformation in the crystalline state as indicated by a dihedral angle of 27.2° formed between isoindole subunits on opposite sides of the core. The ring distortion can be attributed to a combination of steric congestion of the side-chains and the stabilization of the saddle-shaped conformation via pairing of molecules to give the so-called 'overlap effect'. The ring distortion is compared to that found in other metal-free phthalocyanines. Pc 1 adsorbs strongly in the near-IR region, is highly soluble and gives robust spin-coated films of excellent optical clarity.

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Kang, Jong-Hoon, Jong-Woo Kim, Philip J. Ryan, Lin Xie, Lu Guo, Chris Sundahl, Jonathon Schad, et al. "Superconductivity in undoped BaFe2As2by tetrahedral geometry design." Proceedings of the National Academy of Sciences 117, no. 35 (August 17, 2020): 21170–74. http://dx.doi.org/10.1073/pnas.2001123117.

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Fe-based superconductors exhibit a diverse interplay between charge, orbital, and magnetic ordering. Variations in atomic geometry affect electron hopping between Fe atoms and the Fermi surface topology, influencing magnetic frustration and the pairing strength through changes of orbital overlap and occupancies. Here, we experimentally demonstrate a systematic approach to realize superconductivity without chemical doping in BaFe2As2, employing geometric design within an epitaxial heterostructure. We control both tetragonality and orthorhombicity in BaFe2As2through superlattice engineering, which we experimentally find to induce superconductivity when the As−Fe−As bond angle approaches that in a regular tetrahedron. This approach to superlattice design could lead to insights into low-dimensional superconductivity in Fe-based superconductors.

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Shanmugam, Ramalingam. "The lengths of spinal curvature stretch due to the angles of sitting on saddle chair to alleviate back pain: A statistical analysis." Work 68, no. 4 (April 27, 2021): 1027–33. http://dx.doi.org/10.3233/wor-213433.

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BACKGROUND: By dividing the burden of one’s weight between the shins and the buttocks in the sitting position on an office or saddle chair, a person can avoid back pain. In this 21st century, sitting on a chair for long hours in workplace on office chair is unavoidable necessity and hence, millions in different countries undergo a risk for backpain. Is there a right sitting position? OBJECTIVE: The aim of this article is to find out how much a correlation exists between the angle of sitting and the length of spinal curvature which is the source of backpain. An experiment can be designed and carried out to measure various angles in sitting and the changing length of the person’s spinal cord curvature. METHOD: The usual statistical methodology requires a pair of values namely x and y to quantify the correlation. The data on sitting angles and the length of spinal curvature do not have such pairing, and hence, the traditional approach to find the correlation between the sitting angle and length of spinal curvature is not applicable. Yet, an approach is necessary. This article constructs an innovative statistical approach to fulfil this need. RESULTS: Our approach yields a correlation of 0.998 for sitting on office chair and an increased correlation of 0.999 on saddle chair, according to the Truszczyńska-Baszaka et al.’s data. CONCLUSIONS: An adjustment is made in various angles of sitting on office chair to transform the comfortable sitting on a saddle chair. In consequence, the proportional effect on the spinal curvature is estimable with the data and it is phenomenal (that is significantly more than one). No wonder people prefer saddle chair over office chair when it comes to avoid back pain and this article proves the convenience statistically.

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Shigekawa, Koshin, Kosuke Nakayama, Masato Kuno, Giao N. Phan, Kenta Owada, Katsuaki Sugawara, Takashi Takahashi, and Takafumi Sato. "Dichotomy of superconductivity between monolayer FeS and FeSe." Proceedings of the National Academy of Sciences 116, no. 49 (November 19, 2019): 24470–74. http://dx.doi.org/10.1073/pnas.1912836116.

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The discovery of high-temperature (Tc) superconductivity in monolayer FeSe on SrTiO3 raised a fundamental question: Whether high Tc is commonly realized in monolayer iron-based superconductors. Tetragonal FeS is a key material to resolve this issue because bulk FeS is a superconductor with Tc comparable to that of isostructural FeSe. However, difficulty in synthesizing tetragonal monolayer FeS due to its metastable nature has hindered further investigations. Here we report elucidation of band structure of monolayer FeS on SrTiO3, enabled by a unique combination of in situ topotactic reaction and molecular-beam epitaxy. Our angle-resolved photoemission spectroscopy on FeS and FeSe revealed marked similarities in the electronic structure, such as heavy electron doping and interfacial electron–phonon coupling, both of which have been regarded as possible sources of high Tc in FeSe. However, surprisingly, high-Tc superconductivity is absent in monolayer FeS. This is linked to the weak superconducting pairing in electron-doped multilayer FeS in which the interfacial effects are absent. Our results strongly suggest that the cross-interface electron–phonon coupling enhances Tc only when it cooperates with the pairing interaction inherent to the superconducting layer. This finding provides a key insight to explore heterointerface high-Tc superconductors.

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Chen, Xueqiang, Chenghua Wang, and Xiaofei Zhang. "DOA and Noncircular Phase Estimation of Noncircular Signal via an Improved Noncircular Rotational Invariance Propagator Method." Mathematical Problems in Engineering 2015 (2015): 1–12. http://dx.doi.org/10.1155/2015/235173.

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We consider the computationally efficient direction-of-arrival (DOA) and noncircular (NC) phase estimation problem of noncircular signal for uniform linear array. The key idea is to apply the noncircular propagator method (NC-PM) which does not require eigenvalue decomposition (EVD) of the covariance matrix or singular value decomposition (SVD) of the received data. Noncircular rotational invariance propagator method (NC-RI-PM) avoids spectral peak searching in PM and can obtain the closed-form solution of DOA, so it has lower computational complexity. Animproved NC-RI-PMalgorithm of noncircular signal for uniform linear array is proposed to estimate the elevation angles and noncircular phases with automatic pairing. We reconstruct the extended array output by combining the array output and its conjugated counterpart. Our algorithm fully uses the extended array elements in the improved propagator matrix to estimate the elevation angles and noncircular phases by utilizing the rotational invariance property between subarrays. Compared with NC-RI-PM, the proposed algorithm has better angle estimation performance and much lower computational load. The computational complexity of the proposed algorithm is analyzed. We also derive the variance of estimation error and Cramer-Rao bound (CRB) of noncircular signal for uniform linear array. Finally, simulation results are presented to demonstrate the effectiveness of our algorithm.

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Dzhumanov, S., E. X. Karimboev, and Sh S. Djumanov. "Unrelated BCS-like pairing pseudogap and critical superconducting transition temperature in various cuprate compounds." Modern Physics Letters B 32, no. 18 (June 27, 2018): 1850195. http://dx.doi.org/10.1142/s0217984918501956.

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The smooth evolution of the energy gap observed in the tunneling and angle-resolved photoemission spectra (ARPES) of high-[Formula: see text] cuprates with lowering the temperature from a pseudogap state above the critical temperature [Formula: see text] to a superconducting state below [Formula: see text], has been poorly interpreted as the evidence that the pseudogap must have the same origin as the superconducting order parameter, and therefore, must be related to [Formula: see text]. We argue that such an explanation of the tunneling gap and ARPES data is misleading. We show that the BCS-like energy gap (or pseudogap) opening in the electronic excitation spectrum of underdoped-to-overdoped cuprates at a characteristic temperature [Formula: see text] and the true superconducting order parameter appearing only at [Formula: see text] are unrelated. The superconducting phenomenon in unconventional cuprate superconductors is fundamentally different from the BCS-like pairing of fermionic quasiparticles, and the superconducting transition temperature [Formula: see text] is not determined by the BCS-like gap formation. The unusual superconducting order parameter in these high-[Formula: see text] materials appears at [Formula: see text] and coexists with the BCS-like gap (or pseudogap) below [Formula: see text].

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Eskildsen, Morten. "Vortex Lattice Studies in Type-II Superconductors by SANS." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C144. http://dx.doi.org/10.1107/s2053273314098556.

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When a type-II superconductor is placed in a magnetic field, it is threaded by swirling whirlpools of electric current known as vortices. The vortices behave like massive entities and provide a unique probe into the nature of the superconducting state in the host material. Furthermore, the collective vortex behavior is of crucial importance for practical applications since vortex motion will lead to dissipation. I will discuss two recent vortex lattice (VL) studies using small-angle neutron scattering (SANS) that exemplify the continuous evolution of this technique. In the first example we used SANS to determine the superconducting anisotropy of Sr2RuO4 (SRO) that is among the few superconductors believed to exhibit p-wave pairing [1]. While there is significant experimental support for unconventional pairing, there is a discrepancy between the anisotropies of the upper critical field and the Fermi surface. Taking advantage of the significant transverse VL field component that arises due to the large anisotropy of SRO we measured the superconducting anisotropy ≍ 60, roughly three times greater than the upper critical field anisotropy. This result imposes significant constraints on possible models of triplet pairing in SRO. In the second example we used a stop-motion technique to study VL transition dynamics in MgB2 [2,3]. Here the VL exhibit extensive metastability in connection with a second order rotational phase transition that cannot be understood based on the single VL domain free energy or vortex pinning. Instead, we have proposed that a jamming of VL domains acting as granular entities is responsible for the metastability. We have performed extensive SANS experiments, as the VL is driven from the metastable to the ground state by small-amplitude AC magnetic field oscillations. This shows a dual power-law behavior indicating a two-step process for the transition to the ground state. Supported by the US Department of Energy (Grant No. DE-FG02-10ER46783).

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SUMNER, D., S. J. PRICE, and M. P. PAÏDOUSSIS. "Flow-pattern identification for two staggered circular cylinders in cross-flow." Journal of Fluid Mechanics 411 (May 25, 2000): 263–303. http://dx.doi.org/10.1017/s0022112099008137.

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The flow around two circular cylinders of equal diameter, arranged in a staggered configuration, was investigated using flow visualization and particle image velocimetry for centre-to-centre pitch ratio P/D = 1[ratio ]0 to 5.0 and angle of incidence. α = 0° to 90°. Experiments were conducted within the low subcritical Reynolds number regime, from Re = 850 to 1900. Nine flow patterns were identified, and processes of shear layer reattachment, induced separation, vortex pairing and synchronization, and vortex impingement, were observed. New insight was gained into previously published Strouhal number data, by considering the flow patterns involved. The study revealed that vortex shedding frequencies are more properly associated with individual shear layers than with individual cylinders; more specifically, the two shear layers from the downstream cylinder often shed vortices at different frequencies.

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Hashimoto, Takahiro, Yuichi Ota, Akihiro Tsuzuki, Tsubaki Nagashima, Akiko Fukushima, Shigeru Kasahara, Yuji Matsuda, et al. "Bose-Einstein condensation superconductivity induced by disappearance of the nematic state." Science Advances 6, no. 45 (November 2020): eabb9052. http://dx.doi.org/10.1126/sciadv.abb9052.

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The crossover from the superconductivity of the Bardeen-Cooper-Schrieffer (BCS) regime to the Bose-Einstein condensation (BEC) regime holds a key to understanding the nature of pairing and condensation of fermions. It has been mainly studied in ultracold atoms, but in solid systems, fundamentally previously unknown insights may be obtained because multiple energy bands and coexisting electronic orders strongly affect spin and orbital degrees of freedom. Here, we provide evidence for the BCS-BEC crossover in iron-based superconductors FeSe1 − xSx from laser-excited angle-resolved photoemission spectroscopy. The system enters the BEC regime with x = 0.21, where the nematic state that breaks the orbital degeneracy is fully suppressed. The substitution dependence is opposite to the expectation for single-band superconductors, which calls for a new mechanism of BCS-BEC crossover in this system.

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38

Feng, Hao, Lutao Liu, and Biyang Wen. "2D-DOA Estimation for Cylindrical Array with Mutual Coupling." Mathematical Problems in Engineering 2014 (2014): 1–8. http://dx.doi.org/10.1155/2014/716978.

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Most conventional direction-of-arrival (DOA) estimation algorithms are affected by the effect of mutual coupling, which make the performance of DOA estimation degrade. In this paper, a novel DOA estimation algorithm for conformal array in the presence of unknown mutual coupling is proposed. The special mutual coupling matrix (MCM) is applied to eliminate the effect of mutual coupling. With suitable array design, the decoupling between polarization parameter and angle information is accomplished. The two-demission DOA (2D-DOA) estimation is finally achieved based on estimation of signal parameters via rotational invariance techniques (ESPRIT). The proposed algorithm can be extended to conical conformal array as well. Two parameter pairing methods are illustrated for cylindrical and conical conformal array, respectively. The computer simulation verifies the effectiveness of the proposed algorithm.

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Park, Gyuri, Byunghwa Kang, Soyeon V. Park, Donghwa Lee, and Seung Soo Oh. "A unified computational view of DNA duplex, triplex, quadruplex and their donor–acceptor interactions." Nucleic Acids Research 49, no. 9 (April 24, 2021): 4919–33. http://dx.doi.org/10.1093/nar/gkab285.

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Abstract DNA can assume various structures as a result of interactions at atomic and molecular levels (e.g., hydrogen bonds, π–π stacking interactions, and electrostatic potentials), so understanding of the consequences of these interactions could guide development of ways to produce elaborate programmable DNA for applications in bio- and nanotechnology. We conducted advanced ab initio calculations to investigate nucleobase model structures by componentizing their donor-acceptor interactions. By unifying computational conditions, we compared the independent interactions of DNA duplexes, triplexes, and quadruplexes, which led us to evaluate a stability trend among Watson–Crick and Hoogsteen base pairing, stacking, and even ion binding. For a realistic solution-like environment, the influence of water molecules was carefully considered, and the potassium-ion preference of G-quadruplex was first analyzed at an ab initio level by considering both base-base and ion-water interactions. We devised new structure factors including hydrogen bond length, glycosidic vector angle, and twist angle, which were highly effective for comparison between computationally-predicted and experimentally-determined structures; we clarified the function of phosphate backbone during nucleobase ordering. The simulated tendency of net interaction energies agreed well with that of real world, and this agreement validates the potential of ab initio study to guide programming of complicated DNA constructs.

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Zhang, Fang, Masaru Tsunoda, Kaoru Suzuki, Yuji Kikuchi, Oliver Wilkinson, Christopher Millington, Geoffrey Margison, David Williams, and Akio Takénaka. "O6-carboxymethyl-G forms a sequence context dependent wobble base pair with T." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C215. http://dx.doi.org/10.1107/s2053273314097848.

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Previously, we reported the crystal structure of DNA d(CGCGXATTCGCG), which revealed that X (O6-carboxymethyl-G) at the 5th position forms a Watson-Crick (WC) type pair with T (Fig. 1a) similar to the canonical A:T pair [1]. In order to investigate the versatility of X in the base-pair formation, another DNA d(CGCXAATTTGCG) containing X at the 4th position has been X-ray analyzed using four different crystals. In the four crystals, the T bases are always largely wobbled into the major groove side to form a hydrogen bond between N3 of T and the carboxyl group of X. In addition, a water molecule bridges between the two bases through two hydrogen bonds to stabilize the pair formation (Fig.1b). This high-wobble (hW) pair is quite different from the previously reported one [1]. Now we succeeded to reveal the two types of pairing modes of X:T pair, WC type and hW type. Since the four crystals were obtained in different conditions, the large displacement of T cannot be ascribed to the interactions with solvent cations. Another possibility is Hoechst33258 used for crystallization. But, as the crystals were obtained in both the presence and the absence of Hoechst33258, this is not the case. The remaining possibility would be the location of the modified base, because the sequence of the used DNA contains an AATT tract at the center and two CGCG tracts at the both ends. The AATT tract is well known to be more flexible (ω*≍ -160) than CGCG tract (ω*≍ -8.70). We found that the WC type X:T pairing requires a large ω angle (-180) between the bases. When X is located at the 5th position (in the AATT tract), the WC type is allowed to occur, while at the 4th position (in the CGCG tract) the WC type is difficult to occur. Here it could be concluded that X form a pair with T in the mode of WC if it is in the flexible tract, while in the mode of hW if it is in the rigid tract, because T base is out of the base stacking. * propeller twist angle between the two bases.

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Ferre, F., Y. Ponty, W. A. Lorenz, and P. Clote. "DIAL: a web server for the pairwise alignment of two RNA three-dimensional structures using nucleotide, dihedral angle and base-pairing similarities." Nucleic Acids Research 35, Web Server (May 8, 2007): W659—W668. http://dx.doi.org/10.1093/nar/gkm334.

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Liu, Li, Lin Wei, and Zhi Hong Liu. "Finite Element Simulation of the Artificial Knee-Joints of Similar Type Pairing." Applied Mechanics and Materials 300-301 (February 2013): 243–47. http://dx.doi.org/10.4028/www.scientific.net/amm.300-301.243.

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The stress relationship between several pairings was studied through the contrastive contact analysis between the artifical knee-joints of the same type pairing and similar type pairing in different angles and conditions to expand the application of the existing artifical knee-joints. The result shows that, the maximal equivalent stresses of the artifical knee-joints of similar type pairing are more than those of the artifical knee-joints of the same type pairing generally. The law is especially clear in conditions of larger force. In conditions of walking on the flat ground and climbing the stairs, the stress growths between 4/3 pairing and 3/3 pairing are the largest in 10° , they are 18.3% and 14.5% respectively; the stress growths between 3/2.5 pairing and 3/3 pairing are the largest in 20° , they are 13.4% and 15% respectively.

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Belhaiza, Slim. "A Hybrid Adaptive Large Neighborhood Heuristic for a Real-Life Dial-a-Ride Problem." Algorithms 12, no. 2 (February 16, 2019): 39. http://dx.doi.org/10.3390/a12020039.

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The transportation of elderly and impaired people is commonly solved as a Dial-A-Ride Problem (DARP). The DARP aims to design pick-up and delivery vehicle routing schedules. Its main objective is to accommodate as many users as possible with a minimum operation cost. It adds realistic precedence and transit time constraints on the pairing of vehicles and customers. This paper tackles the DARP with time windows (DARPTW) from a new and innovative angle as it combines hybridization techniques with an adaptive large neighborhood search heuristic algorithm. The main objective is to improve the overall real-life performance of vehicle routing operations. Real-life data are refined and fed to a hybrid adaptive large neighborhood search (Hybrid-ALNS) algorithm which provides a near-optimal routing solution. The computational results on real-life instances, in the Canadian city of Vancouver and its region, and DARPTW benchmark instances show the potential improvements achieved by the proposed heuristic and its adaptability.

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Daly-Grafstein, Daniel, and Luke Bornn. "Using in-game shot trajectories to better understand defensive impact in the NBA." Journal of Sports Analytics 6, no. 4 (January 7, 2021): 235–42. http://dx.doi.org/10.3233/jsa-200400.

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As 3-point shooting in the NBA continues to increase, the importance of perimeter defense has never been greater. Perimeter defenders are often evaluated by their ability to tightly contest shots, but how exactly does contesting a jump shot cause a decrease in expected shooting percentage, and can we use this insight to better assess perimeter defender ability? In this paper we analyze over 50,000 shot trajectories from the NBA to explain why, in terms of impact on shot trajectories, shooters tend to miss more when tightly contested. We present a variety of results derived from this shot trajectory data. Additionally, pairing trajectory data with features such as defender height, distance, and contest angle, we are able to evaluate not just perimeter defenders, but also shooters’ resilience to defensive pressure. Utilizing shot trajectories and corresponding modeled shot-make probabilities, we are able to create perimeter defensive metrics that are more accurate and less variable than traditional metrics like opponent field goal percentage.

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Goehring, Lucas, Joaquim Li, and Pree-Cha Kiatkirakajorn. "Drying paint: from micro-scale dynamics to mechanical instabilities." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, no. 2093 (April 3, 2017): 20160161. http://dx.doi.org/10.1098/rsta.2016.0161.

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Charged colloidal dispersions make up the basis of a broad range of industrial and commercial products, from paints to coatings and additives in cosmetics. During drying, an initially liquid dispersion of such particles is slowly concentrated into a solid, displaying a range of mechanical instabilities in response to highly variable internal pressures. Here we summarize the current appreciation of this process by pairing an advection-diffusion model of particle motion with a Poisson–Boltzmann cell model of inter-particle interactions, to predict the concentration gradients in a drying colloidal film. We then test these predictions with osmotic compression experiments on colloidal silica, and small-angle X-ray scattering experiments on silica dispersions drying in Hele–Shaw cells. Finally, we use the details of the microscopic physics at play in these dispersions to explore how two macroscopic mechanical instabilities—shear-banding and fracture—can be controlled. This article is part of the themed issue ‘Patterning through instabilities in complex media: theory and applications.’

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Ludbrook, B. M., G. Levy, P. Nigge, M. Zonno, M. Schneider, D. J. Dvorak, C. N. Veenstra, et al. "Evidence for superconductivity in Li-decorated monolayer graphene." Proceedings of the National Academy of Sciences 112, no. 38 (September 8, 2015): 11795–99. http://dx.doi.org/10.1073/pnas.1510435112.

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Monolayer graphene exhibits many spectacular electronic properties, with superconductivity being arguably the most notable exception. It was theoretically proposed that superconductivity might be induced by enhancing the electron–phonon coupling through the decoration of graphene with an alkali adatom superlattice [Profeta G, Calandra M, Mauri F (2012) Nat Phys 8(2):131–134]. Although experiments have shown an adatom-induced enhancement of the electron–phonon coupling, superconductivity has never been observed. Using angle-resolved photoemission spectroscopy (ARPES), we show that lithium deposited on graphene at low temperature strongly modifies the phonon density of states, leading to an enhancement of the electron–phonon coupling of up to λ≃0.58. On part of the graphene-derived π∗-band Fermi surface, we then observe the opening of a Δ≃0.9-meV temperature-dependent pairing gap. This result suggests for the first time, to our knowledge, that Li-decorated monolayer graphene is indeed superconducting, with Tc≃5.9 K.

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Kim, Hyun-Tak. "Analysis of the diverging effective mass in YaBa2Cu3O6+x for high-Tc mechanism and pairing symmetry." International Journal of Modern Physics B 32, no. 17 (July 9, 2018): 1840031. http://dx.doi.org/10.1142/s0217979218400313.

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In order to clarify the high-T[Formula: see text] mechanism in inhomogeneous cuprate layer superconductors, we deduce and find the correlation strength which has not revealed before, contributing to the formation of the Cooper pair and the two-dimensional density of state, and demonstrate the pairing symmetry in the superconductors which is still controversial. To the open questions, the fitting and analysis of the diverging effective mass with decreasing doping, extracted from the acquired quantum-oscillation data in underdoped YaBa2Cu3O[Formula: see text] superconductors, using the extended Brinkman–Rice (BR) picture, reveal the nodal constant Fermi energy with the maximum carrier density, a constant Coulomb correlation strength [Formula: see text]=U/U[Formula: see text]0.90, and a growing Fermi arc from the nodal Fermi point to the isotropic Fermi surface with an increasing x. The growing of the Fermi arc indicates that a superconducting gap develops with x from the node (underdoped) to the anti-node (optimally or over-doped). The large [Formula: see text] results from the [Formula: see text]-wave metal–insulator transition for the pseudogap phase in lightly doped superconductors, which can be direct evidence for high-T[Formula: see text] superconductivity. The quantum critical point is regarded as the nodal Fermi point satisfied with the BR picture. The experimentally measured mass diverging behavior is an average effect and the true effective mass is constant. As an application of the nodal constant carrier density, the superconducting node gap analyzed by an angle-resolved photoemission spectroscopy (ARPES) is a precursor of s-wave symmetry in underdoped cuprates. Furthermore, the half-flux quantum, induced by the circulation of d-wave supercurrent and observed by the phase sensitive Josephson-[Formula: see text] junction experiments, is not shown due to “anisotropic or asymmetric effect” appearing in superconductors with trapped flux.

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Lin, Chun‐Hung, and Wen‐Hsien Fang. "Efficient estimation of signal parameters via rotational invariance technique‐based algorithm with automatic pairing for two‐dimensional angle and polarisation estimation using crossed dipoles." IET Signal Processing 8, no. 4 (June 2014): 309–19. http://dx.doi.org/10.1049/iet-spr.2013.0040.

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Xu, Ding Jie, Mo Xuan Li, and Xian Peng Wang. "Improved Algorithm for Joint DOD and DOA Estimation in Bistatic MIMO Radar Based on Fourth Order Cumulants." Advanced Materials Research 694-697 (May 2013): 2550–56. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.2550.

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An improved algorithm for joint direction of departure (DOD) and direction of arrival (DOA) estimation in bistatic MIMO radar based on fourth order cumulants is presented. Firstly, the data of receiver is reset and divided to acquire the rotational invariance property of transmitter and receiver, respectively. The fourth order cumulants matrixes in twain are constructed which are based on the basic definition of the cumulant. Then we use the propagator method (PM), which only requires linear operation but does not involve any eigendecomposition of the cumulant matrix, to estimate the DODs and DOAs, respectively. Finally, the maximum likelihood method is used to solve the pairing problem. The proposed method is effective in prohibiting the Gaussian colored noise and improves the performance of the angle estimation slightly. It does not need two-dimensional spectrum peak searching and eigenvalue decomposition on the cumulant matrix, thus the computation complexity is reduced. At the same time, it has no exceptive claim on the number of receive arrays or receive arrays. Simulation results verify the effectiveness and feasibility of the proposed method.

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Rajaee, Mojtaba, Sture K. F. Karlsson, and Lawrence Sirovich. "Low-dimensional description of free-shear-flow coherent structures and their dynamical behaviour." Journal of Fluid Mechanics 258 (January 10, 1994): 1–29. http://dx.doi.org/10.1017/s0022112094003228.

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The snapshot form of the Karhunen-Loéve (K–L) expansion has been applied to twodimensional, two-component hot-wire data from the region of a weakly pertubed free shear layer that includes the first pairing process. Low-level external perturbation was provided by a loudspeaker driven by a computer-generated signal composed of two sine waves of equal amplitude at the frequencies of the naturally developing fundamental instability wave and its first subharmonic, separated by a controllable initial phase angle difference. It was found that a large fraction of the fluctuation energy is carried by the first few modes. A low-dimensional empirical eigenfunction space is obtained which describes the shear-flow coherent structures well. Galerkin projection of the Navier-Stokes equations onto this basis set of principal eigenfunction modes results in a low-order system of dynamical equations, and solution of this system of equations describes the dynamics of the coherent structures associated with eigenfunctions. Finally the simulation, as obtained from the system of dynamical equations, is shown to compare reasonably well with the experiments.

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Journal articles on the topic 'Angle pairing'

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