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1
Baum, Eckhard, and Stefan Eberhardt. "Eddy current brake with two pole pairs." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 28, no. 1 (January 2, 2009): 67–76. http://dx.doi.org/10.1108/03321640910918878.
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PurposeThe purpose of this paper is to derive a force‐velocity characteristic for an eddy current brake with minor computational effort.Design/methodology/approachThe speed range is split into two domains. While in the low‐speed domain it is possible to achieve a closed form expression for the force‐velocity characteristic in the high‐speed region approximations have to be introduced.FindingsThe derived relation for the force‐velocity characteristic has been compared with measurement results. The comparison shows that the approach yields good results for not too large air gaps.Originality/valueA combination of analytical and approximative methods has been used for the determination of the force‐velocity characteristic of an eddy current brake with two pole pairs.
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Richa and Awadhesh Kumar. "Dominant Pole Based Approximation for Discrete Time System." International Journal of Mathematical, Engineering and Management Sciences 4, no. 1 (February 1, 2019): 56–65. http://dx.doi.org/10.33889/ijmems.2019.4.1-005.
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This paper presents an effective procedure for model order reduction of discrete time control system. The exact model derived from complex dynamic systems proves to be very complicated for analysis, control and design. This necessity brings about using a tool known as model order reduction technique or model simplification. A novel mixed method has been implemented in this paper for reducing the order of the large scale dynamic discrete system. Dominant pole based pole clustering method has been used to derive the coefficients of denominator polynomial while Padé approximation has been applied to obtain the coefficients of numerator polynomial of the reduced order model. The proposed method is quite simple and able to generate a stable reduced order model from high order stable discrete systems. The dominancy of poles has been decided by values of the ratio of residue to its pole. The pole is considered dominant which have larger ratio value. An illustrative example has been considered to show the various reduction steps. The result obtained confirms the effectiveness of the approach.
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Moale, Ionela, and Veronika Pillwein. "A note on uniform approximation of functions having a double pole." LMS Journal of Computation and Mathematics 17, no. 1 (2014): 233–44. http://dx.doi.org/10.1112/s1461157013000387.
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AbstractWe consider the classical problem of finding the best uniform approximation by polynomials of$1/(x-a)^2,$where$a>1$is given, on the interval$[-\! 1,1]$. First, using symbolic computation tools we derive the explicit expressions of the polynomials of best approximation of low degrees and then give a parametric solution of the problem in terms of elliptic functions. Symbolic computation is invoked then once more to derive a recurrence relation for the coefficients of the polynomials of best uniform approximation based on a Pell-type equation satisfied by the solutions.
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Savyolova, T. I. "Determination of Domains of Dependence Through the Solution of an Ultrahyperbolic Differential Equation." Textures and Microstructures 25, no. 2-4 (January 1, 1996): 183–95. http://dx.doi.org/10.1155/tsm.25.183.
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Pole figures are represented as the sum of solutions of two ultrahyperbolic differential equations. We derive the domains of dependence for pole figures and apply the method of continuation to solve the ultrahyperbolic equations.
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Silva, José Sergio, Daniela Lazzaro, Teresinha Rodrigues, Jorge Márcio Carvano, Fernando Roig, and Roberto Souza. "The IMPACTON Project: Pole and Shape of Eight Near-Earth Asteroids." Proceedings of the International Astronomical Union 10, S318 (August 2015): 181–84. http://dx.doi.org/10.1017/s1743921315008637.
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AbstractThe formation and evolution of Solar System small bodies, in particular those in near-Earth orbits, is a complex problem which solution strongly depends on a better knowledge of their physical properties. To contribute to the international efforts in this direction the IMPACTON project (www.on.br/IMPACTON) set up a dedicated facility denominated Observatório Astronômico do Sertão de Itaparica (OASI). Using the 1-m telescope several dozens of NEAs were observed between March 2012 and October 2014. Here we will present the results obtained for 8 objects. Relative magnitudes were used to obtain lightcurves and derive rotational periods. Applying the inversion method developed by Kaasalainen and Torppa (2001) and Kaasalainen et al. (2001), along with lightcurves from literature, allowed to refine the rotational period of these asteroids as well as to derive their pole direction and shape. The obtained results confirm a lack of poles toward the ecliptic and with a majority of retrograde rotators. A more representative sample, however, is needed in order to drive robust conclusions.
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Wofsy, S. C. "HIAPER Pole-to-Pole Observations (HIPPO): fine-grained, global-scale measurements of climatically important atmospheric gases and aerosols." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 369, no. 1943 (May 28, 2011): 2073–86. http://dx.doi.org/10.1098/rsta.2010.0313.
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The HIAPER Pole-to-Pole Observations (HIPPO) programme has completed three of five planned aircraft transects spanning the Pacific from 85° N to 67° S, with vertical profiles every approximately 2.2° of latitude. Measurements include greenhouse gases, long-lived tracers, reactive species, O 2 /N 2 ratio, black carbon (BC), aerosols and CO 2 isotopes. Our goals are to address the problem of determining surface emissions, transport strength and patterns, and removal rates of atmospheric trace gases and aerosols at global scales and to provide strong tests of satellite data and global models. HIPPO data show dense pollution and BC at high altitudes over the Arctic, imprints of large N 2 O sources from tropical lands and convective storms, sources of pollution and biogenic CH 4 in the Arctic, and summertime uptake of CO 2 and sources for O 2 at high southern latitudes. Global chemical signatures of atmospheric transport are imaged, showing remarkably sharp horizontal gradients at air mass boundaries, weak vertical gradients and inverted profiles (maxima aloft) in both hemispheres. These features challenge satellite algorithms, global models and inversion analyses to derive surface fluxes. HIPPO data can play a crucial role in identifying and resolving questions of global sources, sinks and transport of atmospheric gases and aerosols.
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Lescroart, Fabienne, Wissam Hamou, Alexandre Francou, Magali Théveniau-Ruissy, Robert G. Kelly, and Margaret Buckingham. "Clonal analysis reveals a common origin between nonsomite-derived neck muscles and heart myocardium." Proceedings of the National Academy of Sciences 112, no. 5 (January 20, 2015): 1446–51. http://dx.doi.org/10.1073/pnas.1424538112.
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Neck muscles constitute a transition zone between somite-derived skeletal muscles of the trunk and limbs, and muscles of the head, which derive from cranial mesoderm. The trapezius and sternocleidomastoid neck muscles are formed from progenitor cells that have expressed markers of cranial pharyngeal mesoderm, whereas other muscles in the neck arise from Pax3-expressing cells in the somites. Mef2c-AHF-Cre genetic tracing experiments and Tbx1 mutant analysis show that nonsomitic neck muscles share a gene regulatory network with cardiac progenitor cells in pharyngeal mesoderm of the second heart field (SHF) and branchial arch-derived head muscles. Retrospective clonal analysis shows that this group of neck muscles includes laryngeal muscles and a component of the splenius muscle, of mixed somitic and nonsomitic origin. We demonstrate that the trapezius muscle group is clonally related to myocardium at the venous pole of the heart, which derives from the posterior SHF. The left clonal sublineage includes myocardium of the pulmonary trunk at the arterial pole of the heart. Although muscles derived from the first and second branchial arches also share a clonal relationship with different SHF-derived parts of the heart, neck muscles are clonally distinct from these muscles and define a third clonal population of common skeletal and cardiac muscle progenitor cells within cardiopharyngeal mesoderm. By linking neck muscle and heart development, our findings highlight the importance of cardiopharyngeal mesoderm in the evolution of the vertebrate heart and neck and in the pathophysiology of human congenital disease.
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Halder, Kaushik, Saptarshi Das, and Amitava Gupta. "Transformation of LQR Weights for Discretization Invariant Performance of PI/PID Dominant Pole Placement Controllers." Robotica 38, no. 2 (May 14, 2019): 271–98. http://dx.doi.org/10.1017/s0263574719000596.
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SummaryLinear quadratic regulator (LQR), a popular technique for designing optimal state feedback controller, is used to derive a mapping between continuous and discrete time inverse optimal equivalence of proportional integral derivative (PID) control problem via dominant pole placement. The aim is to derive transformation of the LQR weighting matrix for fixed weighting factor, using the discrete algebraic Riccati equation (DARE) to design a discrete time optimal PID controller producing similar time response to its continuous time counterpart. Continuous time LQR-based PID controller can be transformed to discrete time by establishing a relation between the respective LQR weighting matrices that will produce similar closed loop response, independent of the chosen sampling time. Simulation examples of first/second order and first-order integrating processes exhibiting stable/unstable and marginally stable open loop dynamics are provided, using the transformation of LQR weights. Time responses for set-point and disturbance inputs are compared for different sampling times as fraction of the desired closed loop time constant.
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WERNER, ULRICH. "THEORETICAL VIBRATION ANALYSIS OF SOFT MOUNTED TWO-POLE INDUCTION MOTORS WITH STATIC ROTOR ECCENTRICITY." International Journal of Applied Mechanics 03, no. 01 (March 2011): 131–59. http://dx.doi.org/10.1142/s1758825111000919.
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The paper shows a mathematical model for vibration analysis of soft mounted two-pole induction motors regarding electromagnetic excitation due to static rotor eccentricity. A static rotor eccentricity causes an electromagnetic force, acting on the rotor and on the stator and oscillating with the double supply frequency. This magnetic force is implemented into a simplified analytical machine dynamic model and the correlations between the rotor dynamics, electromagnetic, oil film characteristics of the sleeve bearings, and the stiffness and damping of a soft foundation are mathematically described. The derived results are clarified using an example that shows the influence of the rotor speed and the direction of the magnetic force on the vibration behavior. On one hand the aim of the paper is to show the mathematical correlations, based on a simplified model. On the other hand, the aim is to derive a method for calculating the forced vibrations — as a worst case — caused by a static rotor eccentricity. Therefore, the paper shall prepare the basis for implementing this method in more detailed numerical programs, e.g., finite element programs.
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Gläser, P., I. Haase, and J. Oberst. "A NEW REALIZATION OF THE GLOBAL LUNAR REFERENCE FRAME BASED ON CO-REGISTERED LOLA TRACKS." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3 (April 30, 2018): 397–401. http://dx.doi.org/10.5194/isprs-archives-xlii-3-397-2018.
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We present a method that aligns lunar south and north pole LOLA DTMs using selected LOLA tracks and co-registration techniques. The selected LOLA tracks were then co-registered to the aligned polar DTMs with the aim to create a new LOLA frame of high relative accuracy. At the poles the relative accuracy of the resulting LOLA frame improved in comparison with the original LOLA frame, especially at the north pole. At lower latitudes on the lunar near side we could show that we achieve smaller residuals between our LOLA frame and a photogrammetrically derived reference DTM than with the original LOLA frame. On the far side we could not achieve better results which we believe is stemming from the generally less accurate orbit knowledge there. From the aligned polar DTMs we were able to derive a polar radius of 1738,049 km.
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Kim, J., and W. Soedel. "Development of a General Procedure to Formulate Four Pole Parameters by Modal Expansion and Its Application to Three-Dimensional Cavities." Journal of Vibration and Acoustics 112, no. 4 (October 1, 1990): 452–59. http://dx.doi.org/10.1115/1.2930128.
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If an acoustic system has one or more large dimensions compared to the shortest wave length of interest, the pressure responses which are necessary to formulate four pole parameters have to be obtained by solving the continuous wave equation of the system. In this paper, a general procedure is established to derive four pole parameters from the pressure response solutions utilizing modal series expansion. As an example, four pole parameters of a cylindrically annular cavity are obtained. The validity of the procedure is proven by applying it also to a one-dimensional pipe whose four pole parameters are available by direct method. The comparison is made in terms of four pole parameters and pressure profiles along the pipe. The comparison allows interesting observations with regard to the equivalence of the two approaches. The theory was further generalized to be applied to more complex acoustic systems, namely multiply connected systems. A cylindrically annular cavity connected by two pipes to a small lumped parameter cavity is taken as an example of the application. Noise control by either mode cancellation or wave cancellation is explored.
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Prygarin, Alexander. "Reflection Identities of Harmonic Sums of Weight Four." Universe 5, no. 3 (March 11, 2019): 77. http://dx.doi.org/10.3390/universe5030077.
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In attempt to find a proper space of function expressing the eigenvalue of the color-singlet BFKL equation in N = 4 SYM, we consider an analytic continuation of harmonic sums from positive even integer values of the argument to the complex plane. The resulting meromorphic functions have pole singularities at negative integers. We derive the reflection identities for harmonic sums at weight four decomposing a product of two harmonic sums with mixed pole structure into a linear combination of terms each having a pole at either negative or non-negative values of the argument. The pole decomposition demonstrates how the product of two simpler harmonic sums can build more complicated harmonic sums at higher weight. We list a minimal irreducible set of bilinear reflection identities at weight four, which represents the main result of the paper. We also discuss how other trilinear and quadlinear reflection identities can be constructed from our result with the use of well known quasi-shuffle relations for harmonic sums.
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Van Houtte, P. "A Method for the Generation of Various Ghost Correction Algorithms—the Example of the Positivity Method and the Exponential Method." Textures and Microstructures 13, no. 4 (January 1, 1991): 199–212. http://dx.doi.org/10.1155/tsm.13.199.
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A theoretical strategy is presented that can derive the algorithms of several existing ghost correction methods. The examples of the positivity method and the “GHOST” method are elaborated. A new method is derived as well: the “exponential” method. It can successfully replace the quadratic method as a method that yields an exactly non-negative complete C.O.D.F. from pole figure data. The theoretical scheme that can generate all these algorithms makes use of the fact, that several parameter sets can be defined in order to describe a C.O.D.F. The parameters of one set are then functions of those of the other. The algorithms are derived from Taylor series expansions of these functions.
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Chen, Zhimin, and Lenan Wu. "Design of Special Impacting Filter for Multicarrier ABPSK System." Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/921932.
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A rather intuitive technique known as pole-zero placement is introduced to illustrate the frequency response of the special impacting filters (SIFs) with a pair of conjugate zero-poles and deduce the equation of the pole radii. Based on that, the paper proposes an iterative scheme to derive the parameters of the cascade notch filter. The cost function is determined by the cascading notch filter’s influence on impacting filters, converting the cost function’s least square problem to a filter parameters’ standard quadratic programming problem. Finally, a cascading notch SIF (CNSIF) designed to demodulate the ABPSK signals is realized.
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Konno, Atsushi, Liu Deman, and Masaru Uchiyama. "A singularly perturbed method for pole assignment control of a flexible manipulator." Robotica 20, no. 6 (November 2002): 637–51. http://dx.doi.org/10.1017/s0263574702004435.
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This paper focuses on using a singularly perturbed approach to derive a vibration damping control law in which a pole assignment feedback method is utilized. The composite control system is characterized by two components which can be computed separately. The one is Cartesian-based PI control which drives the end-effector of a flexible manipulator to track the desired time-based trajectory. The other is pole assignment feedback control which damps out vibrations during and at the end of trajectory tracking. An advantage of this composite control method in real implementation is that it does not require a derivative of the end-effector's position, and the derivatives of signals from the strain gauges. From the characteristics and implementation points of view, it appears to be simple to use. Laboratory experiments were conducted to evaluate the performance of the proposed control method.
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Tiang, Tow Leong, Dahaman Ishak, and Chee Peng Lim. "Fourier decomposition of segmented magnets with radial magnetization in surface-mounted PM machines." Journal of Electrical Engineering 68, no. 6 (November 1, 2017): 470–75. http://dx.doi.org/10.1515/jee-2017-0082.
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AbstractThis paper presents a generic field model of radial magnetization (RM) pattern produced by multiple segmented magnets per rotor pole in surface-mounted permanent magnet (PM) machines. The magnetization vectors from either odd- or even-number of magnet blocks per pole are described. Fourier decomposition is first employed to derive the field model, and later integrated with the exact 2D analytical subdomain method to predict the magnetic field distributions and other motor global quantities. For the assessment purpose, a 12-slot/8-pole surface-mounted PM motor with two segmented magnets per pole is investigated by using the proposed field model. The electromagnetic performances of the PM machines are intensively predicted by the proposed magnet field model which include the magnetic field distributions, airgap flux density, phase back-EMF, cogging torque, and output torque during either open-circuit or on-load operating conditions. The analytical results are evaluated and compared with those obtained from both 2D and 3D finite element analyses (FEA) where an excellent agreement has been achieved.
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Vafaee, A., and K. Javidan. "NNLO compatibility between pQCD theory and phenomenology in determination of the b-quark pole and MS¯ running masses." Modern Physics Letters A 35, no. 30 (August 6, 2020): 2050253. http://dx.doi.org/10.1142/s0217732320502533.
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This contribution attempts to determine the [Formula: see text]-quark pole mass [Formula: see text] and [Formula: see text] running mass [Formula: see text] with two different approaches at the next-to-next-to-leading order (NNLO) corrections. At the first approach, we derive a relation between the [Formula: see text]-quark pole mass [Formula: see text] and its [Formula: see text] running mass [Formula: see text] at the NNLO corrections based on the perturbative Quantum Chromo Dynamics (pQCD) predictions. At the second approach, we extract numerical values of the [Formula: see text]-quark pole and [Formula: see text] running masses based on the NNLO phenomenology of H1 and ZEUS Collaborations combined beauty vertex production experimental data. Then we discuss about the compatibility between the pQCD theory results and phenomenology approach in determination of the [Formula: see text]-quark pole and [Formula: see text] running masses at the NNLO corrections. Also, we investigate the role and influence of the [Formula: see text]-quark mass as an extra degree of freedom added to the input parameters of the Standard Model Lagrangian, on the improvement of the uncertainty band of the proton parton distribution functions (PDFs) and particularly on the gluon distribution.
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Zhu, Yaozhong, and Buxi Gao. "Dissipation and Ellipticity of the Chandler Wobble." International Astronomical Union Colloquium 178 (2000): 473–80. http://dx.doi.org/10.1017/s0252921100061625.
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AbstractThe Chandler wobble, one of the main feature of the Earth’s polar motion, is related to the properties of the mantle and liquid core as well as the mobility of the oceans. The equilibrium pole tide and mantle anelasticity both lengthen the Chandler period, moreover, the former imposes a slight ellipticity on the pole path, and the latter is responsible for the wobble energy dissipation. On the basis of the perturbation principles, we derive the theoretical Qω of the Chandler wobble, assuming that the wobble energy is totally dissipated within the mantle. The theoretical ellipticity and orientation of the semimajor axis of the Chandler wobble path for an anelastic Earth are given. Compared with the results for the elastic Earth, the effect of mantle anelasticity does not change the wobble ellipticity significantly, but slightly changes the orientation of the semimajor axis in the opposite direction. This paper has also proved that the effect of the Earth’s 3-axis feature on the wobble ellipticity is only about 19% of that of the equilibrium pole tide. Analysis of the polar motion data obtained by using modern geodetic techniques shows that the observed ellipticity and orientation of the semimajor axis agree with the theoretical results. We can deduce that the pole tide in the globe should be close to equilibrium.
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Pai, Kai-Jun. "A Reformatory Model Incorporating PNGV Battery and Three-Terminal-Switch Models to Design and Implement Feedback Compensations of LiFePO4 Battery Chargers." Electronics 8, no. 2 (January 24, 2019): 126. http://dx.doi.org/10.3390/electronics8020126.
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This study developed and implemented a LiFePO4 battery pack (LBP) rapid charger. Using the three-terminal switch and partnership for a new generation of vehicles (PNGV) battery models, this study could obtain a small-signal system matrix to derive transfer functions and further analyze frequency responses for the charge voltage and current loops; therefore, both voltage and current feedback controllers could be designed to fulfill the constant-voltage (CV) and constant-current (CC) charges. To address practical applications, the proposed equivalent model also considered the wire resistance-inductance of the power cable. According to the derived high-order transfer function, the pole-zero break frequency in the Bode plot was observed that approximated the practical measurement; therefore, the pole-zero compensation could be accomplished for both charge loop requirements. Moreover, the design features for implementing the CV and CC charges are presented in detail herein, and the current overshoot during the start-up phase could be mitigated using the method of zero break frequency shifting and a novel proportional shifting proportional-integral control. The LBP parameter estimations, model construction processes, and frequency response analyses are also presented. The feedback compensation design based on the proposed model was validated through simulations and experiments. The results were determined to be in excellent agreement with theoretical derivations.
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DAS, SUMIT R., AVINASH DHAR, GAUTAM MANDAL, and SPENTA R. WADIA. "W-INFINITY WARD IDENTITIES AND CORRELATION FUNCTIONS IN THE c=1 MATRIX MODEL." Modern Physics Letters A 07, no. 11 (April 10, 1992): 937–53. http://dx.doi.org/10.1142/s0217732392000835.
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We explore consequences of W-infinity symmetry in the fermionic field theory of the c=1 matrix model. We derive exact Ward identities relating correlation functions of the bilocal operator. These identities can be expressed as equations satisfied by the effective action of a three-dimensional theory and contain non-perturbative information about the model. We use these identities to calculate the two-point function of the bilocal operator in the double scaling limit. We extract the operator whose two-point correlator has a single pole at an (imaginary) integer value of the energy. We then rewrite the W-infinity charges in terms of operators in the matrix model and use this to derive constraints satisfied by the partition function of the matrix model with a general time dependent potential.
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Trefzger, Ch F., J. W. Pel, and A. Blaauw. "Stellar chemical-abundance gradient in the direction of the South Galactic Pole - preliminary results." Symposium - International Astronomical Union 106 (1985): 151–52. http://dx.doi.org/10.1017/s0074180900242277.
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Using the Walraven VBLUW photometric system, we have studied the metal content of 89 F and G stars in the Galactic South Pole field SA141. Our sample is based on the Basel survey of RGU photometry in Selected Areas, and it contains all stars in SA141 with VJ <14m.5 and (G-R)<1m.15 (spectral types earlier than about G7). The observations were made with the VBLUW photometer and the 90-cm Dutch Telescope at ESO, La Silla.For unreddened intermediate-type stars the VBLUW photometry enables us to separate the effects of temperature, gravity, and metallicity (cf. Lub and Pel, 1977). Since reddening is negligible in SA141, we can therefore determine these three parameters for each program star once the photometric indices are calibrated in terms of Teff, log g, and [Fe/H]. The latter calibration was made in a semi-empirical way, using VBLUW observations of stars with spectroscopic analyses in combination with theoretical colors based on the model spectra by Kurucz (1979). We used the Hyades main-sequence as a zeropoint, adopting [Fe/H] = +0.15 for this cluster.The results in the (V-B)-(B-L) diagram are shown in Fig. 1. This diagram is very sensitive to metallicity, but almost gravity-independent. Fig. 1 indicates that most program stars have metallicities in the range −1 ≦ [Fe/H] ≦ 0. The distribution of the program stars in the gravity-sensitive (V-B)-(L-U) diagram is very narrow, log g =4.2 ± 0.3, which means that these stars are probably all dwarfs, with only very few possible subgiants.The absolute-magnitude calibration was derived by using the data of Cayrel de Strobel et al. (1980) and of Cayrel de Strobel and Bentolila (1983). From their [Fe/H]-catalogue we took all stars with known distances, and within the parameter range of our program stars, to construct an empirical MV - Teff relation. This relation was used to derive distances for the stars in SA141.These distances are plotted against [Fe/H] in Fig. 2. The diagram clearly shows the correlation between distance and metallicity, suggesting for this particular sample a gradient of −0.6 in [Fe/H] over the first 500 pc. Similar values were found in the Basel RGU program (cf. Trefzger, 1981) and by Blaauw and Garmany (1975).
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Joubat, Mohammad, and Alexander Prygarin. "The analytic structure of the BFKL equation and reflection identities of harmonic sums at weight five." International Journal of Modern Physics A 34, no. 11 (April 20, 2019): 1950064. http://dx.doi.org/10.1142/s0217751x19500647.
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We analyze the structure of the eigenvalue of the color-singlet Balitsky–Fadin–Kuraev–Lipatov (BFKL) equation in N[Formula: see text]=[Formula: see text]4 SYM in terms of the meromorphic functions obtained by the analytic continuation of harmonic sums from positive even integer values of the argument to the complex plane. The meromorphic functions we discuss have pole singularities at negative integers and take finite values at all other points. We derive the reflection identities for harmonic sums at weight five decomposing a product of two harmonic sums with mixed pole structure into a linear combination of terms each having a pole at either negative or non-negative values of the argument. The pole decomposition demonstrates how the product of two simpler harmonic sums can build more complicated harmonic sums at higher weight. We list a minimal irreducible set of bilinear reflection identities at weight five which presents the main result of the paper. We show how the reflection identities can be used to restore the functional form of the next-to-leading eigenvalue of the color-singlet BFKL equation in N[Formula: see text]=4[Formula: see text]SYM, i.e. we argue that it is possible to restore the full functional form on the entire complex plane provided one has information how the function looks like on just two lines on the complex plane. Finally we discuss how nonlinear reflection identities can be constructed from our result with the use of well known quasi-shuffle relations for harmonic sums.
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Goodness, Devet. "The Nature and Direction of Meaning of -Kali in Kiswahili." Utafiti 13, no. 1 (March 18, 2018): 103–23. http://dx.doi.org/10.1163/26836408-01301008.
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This paper examines the collocations of an adjective stem -kali to create several meanings, showing how -kali can be used to express a wide range of distinct concepts in different occasions of its utterance. It is noted that the few existing studies of Kiswahili adjectives (Ashton 1947, Myachina 1981, Kahigi 2008) which have focused mainly on semantics in determining their meanings, are therefore incomplete because they have overlooked many further meanings of these adjectives in use. Here it is argued that meanings of Kiswahili adjectives can best be exhausted if one takes pragmatics into consideration. This study demonstrates that –kali generates an infinite number of meanings; some of these connotations extend in the direction of negative pole of undesirable attributes and others towards a positive pole. The paper further demonstrates that although the meaning of the adjective stem -kali connoting ‘harsh’ or ‘rude’ can be adjusted pragmatically in context, the different meanings created when this qualifier co-occurs with different nouns derive interestingly from the same stem meaning: ‘harsh’ or’ rude’.
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Rondón, Eduardo, and Ignacio Ferrín. "A Simple Model for the Secular Light Curve of Comet C/1996 B2 Hyakutake." Proceedings of the International Astronomical Union 5, S263 (August 2009): 293–97. http://dx.doi.org/10.1017/s1743921310001961.
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AbstractThe secular light curves of comets (Ferrín, 2005) give a large amount of physical information on the cometary nucleus. We have developed a model that allows the prediction of a secular light curve, from which we derive parameters like the orientation of the rotational axis (I, φ) and optical thickness of the cometary coma. The model is based on the paper published by (Cowan & A'Hearn, 1979). To do the calculation we found a correlation between the water production rate and the reduced magnitude. We obtain probable orientations of the nucleus pole for several combinations of parameters for comet C/1996 B2 Hyakutake.
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RADWAN, A. G., A. M. SOLIMAN, and A. S. ELWAKIL. "FIRST-ORDER FILTERS GENERALIZED TO THE FRACTIONAL DOMAIN." Journal of Circuits, Systems and Computers 17, no. 01 (February 2008): 55–66. http://dx.doi.org/10.1142/s0218126608004162.
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Traditional continuous-time filters are of integer order. However, using fractional calculus, filters may also be represented by the more general fractional-order differential equations in which case integer-order filters are only a tight subset of fractional-order filters. In this work, we show that low-pass, high-pass, band-pass, and all-pass filters can be realized with circuits incorporating a single fractance device. We derive expressions for the pole frequencies, the quality factor, the right-phase frequencies, and the half-power frequencies. Examples of fractional passive filters supported by numerical and PSpice simulations are given.
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Choi, S., Y. Wang, R. J. Salawitch, T. Canty, J. Joiner, T. Zeng, T. P. Kurosu, et al. "Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC." Atmospheric Chemistry and Physics Discussions 11, no. 9 (September 21, 2011): 26173–243. http://dx.doi.org/10.5194/acpd-11-26173-2011.
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Abstract. We derive estimates of tropospheric BrO column amounts during two Arctic field campaigns in 2008 using information from the satellite UV nadir sensors Ozone Monitoring Instrument (OMI) and the second Global Ozone Monitoring Experiment (GOME-2) as well as estimates of stratospheric BrO columns from a model simulation. The sensitivity of the satellite-derived tropospheric BrO columns to various parameters is investigated using a radiative transfer model. We conduct a comprehensive analysis of satellite-derived tropospheric BrO columns including a detailed comparison with aircraft in-situ observations of BrO and related species obtained during the field campaigns. In contrast to prior expectation, tropospheric BrO, when present, existed over a broad range of altitudes. Our results show reasonable agreement between tropospheric BrO columns derived from the satellite observations and columns found using aircraft in-situ BrO. After accounting for the stratospheric contribution to total BrO column, several events of rapid BrO activation due to surface processes in the Arctic are apparent in both the OMI and GOME-2 based tropospheric columns. The wide orbital swath of OMI allows examination of the evolution of tropospheric BrO on about hourly time intervals near the pole. Low pressure systems, strong surface winds, and high planetary boundary layer heights are associated with the observed tropospheric BrO activation events.
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LYKKEN, JOSEPH D., JACOB SONNENSCHEIN, and NATHAN WEISS. "FIELD-THEORETICAL ANALYSIS OF ANYONIC SUPERCONDUCTIVITY." International Journal of Modern Physics A 06, no. 08 (March 30, 1991): 1335–68. http://dx.doi.org/10.1142/s0217751x9100071x.
Full textAbstract:
We derive several results pertaining to anyonic superconductivity as described by a Chern-Simons field theory. (1) The renormalized Chern-Simons term at finite density is shown to vanish when the renormalized coefficient at zero density takes values Ne2/2π. This is the field-theoretical requirement to have a massless pole in the current-current correlator. We can then show that in the Chern-Simons description a system of charged anyons at zero temperature is a superconductor. This result is shown to hold to all orders in perturbation theory by generalizing a nonrenormalization theorem of the zero density case. (2) At finite temperature the renormalized Chern-Simons term does not vanish at the one-loop perturbative level. We compute the mass of this apparent “pseudo-Goldstone mode”. We also exhibit an effect suggestive of critical behavior, for this same system, at a nonzero Tc. We discuss the possible implications of these perturbative results. (3) A low energy effective action for an anyonic superconductor is derived directly from Chern-Simons field theory. Several P and T violating effects occur.
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Küchler, Benjamin, Uwe Schmidt, and Jonathan Hänsch. "Harmonic Current Distribution in Grounding Systems of Cabled Medium Voltage Grids during Single-Pole Ground Fault." Energies 14, no. 4 (February 19, 2021): 1110. http://dx.doi.org/10.3390/en14041110.
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The design of every power supply system must guarantee the safety for human life even in the event of a fault. Due to the system change in the electrical power supply, the fault current contains more and more unknown shares of current harmonics. Especially in medium voltage grids, which are operated with resonant grounding, these are determining for the level of the single-pole ground fault current for determination of permissible touch voltages and compliance with the normative requirements of the European standard EN 50522 must therefore be re-evaluated. In its first part, this concept paper presents the frequency dependent principles of earth loops formed by the grounding system. The focus here is on cabled grids and the influence of connected structures of the low voltage grid. The second part deals with the superposition of these loop currents and the resulting earth currents in case of a line to ground fault. The authors address explicitly the frequency dependence of the current distribution and describe the expected behaviour for current harmonics. The proposed approaches result from processing the state of knowledge, research work and the evaluation of several measurements. The aim is to develop an understanding of the influence of the components connected to a grounding system and to derive generally applicable principles. Therefore, the authors present the results of recent measurements in the last part of the handed paper and point out the possibilities and limits of modeling. It is shown that a dedicated treatment of harmonic currents in the case of a single-pole fault is possible with the methods described. This allows these to be neglected in the estimation of touch voltages under specified circumstances, saving costs for the assessment of grounding systems.
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Vinay, Thurai, Bradley Postma, and Theo Kangsanant. "Dynamic Modeling and Control of Dual Wheeled Mobile Robots Compliantly Coupled to a Common Payload." Journal of Dynamic Systems, Measurement, and Control 121, no. 3 (September 1, 1999): 457–61. http://dx.doi.org/10.1115/1.2802496.
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Lagrange formalism is applied to derive a dynamic model, and design a nonlinear controller for two nonholonomic, differentially steered, wheeled mobile robots compliantly linked to a common payload. The resulting multivariable system model is of a large order and can be block decoupled by selective state feedback into five independent subsystems, two of which effectively represent the deviation dynamics of the individual robots from a prescribed path; two others represent their forward motion dynamics; while the fifth describes the payload dynamics. Controllers for each of the robot subsystems, including self-tuning adaptive controllers for the nonlinear deviation dynamics subsystems, are designed by the pole-placement technique. System performance is then evaluated via simulation for the case where each robot is undergoing curvilinear motion.
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Town, Michael S., Von P. Walden, and Stephen G. Warren. "Cloud Cover over the South Pole from Visual Observations, Satellite Retrievals, and Surface-Based Infrared Radiation Measurements." Journal of Climate 20, no. 3 (February 1, 2007): 544–59. http://dx.doi.org/10.1175/jcli4005.1.
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Abstract Estimates of cloud cover over the South Pole are presented from five different data sources: routine visual observations (1957–2004; Cvis), surface-based spectral infrared (IR) data (2001; CPAERI), surface-based broadband IR data (1994–2003; Cpyr), the Extended Advanced Very High Resolution Radiometer (AVHRR) Polar Pathfinder (APP-x) dataset (1994–99; CAPP-x), and the International Satellite Cloud Climatology Project (ISCCP) dataset (1994–2003; CISCCP). The seasonal cycle of cloud cover is found to range from 45%–50% during the short summer to a relatively constant 55%–65% during the winter. Relationships between Cpyr and 2-m temperature, 10-m wind speed and direction, and longwave radiation are investigated. It is shown that clouds warm the surface in all seasons, 0.5–1 K during summer and 3–4 K during winter. The annual longwave cloud radiative forcing is 18 W m−2 for downwelling radiation and 10 W m−2 for net radiation. The cloud cover datasets are intercompared during the time periods in which they overlap. The nighttime bias of Cvis is worse than previously suspected, by approximately −20%; CISCCP shows some skill during the polar day, while CAPP-x shows some skill at night. The polar cloud masks for the satellite data reviewed here are not yet accurate enough to reliably derive surface or cloud properties over the East Antarctic Plateau. The best surface-based source of cloud cover in terms of the combination of accuracy and length of record is determined to be Cpyr. The use of the Cpyr dataset for further tests of satellite retrievals and for tests of polar models is recommended.
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D'Ajello Caracciolo, F., A. Pignatelli, F. Speranza, and A. Meloni. "A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes." Solid Earth Discussions 3, no. 1 (January 18, 2011): 19–42. http://dx.doi.org/10.5194/sed-3-19-2011.
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Abstract. Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleo)secular variation ((P)SV) are available. To this end, we re-evaluate the whole Italian geomagnetic directional data set, consisting of 833 and 696 declination and inclination (respectively) measurements carried out since 1640 AD at several localities. All directions were relocated via virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E), rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method) by French data (for period 1670–1789), and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962). Using post-1805 declination values, we obtain a 0.46 ± 0.19 °/yr westward drift of the geomagnetic field for Italy. Original observation years were modified considering such drift value to derive a drift-corrected relocated data set. Both data sets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000) and Pavon-Carrasco et al. (2009). However, the drift-corrected data set minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated data sets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. Curve comparison suggests that the regional model by Pavon-Carrasco et al. (2009) yields the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the XIX century. For the XX century, the global model by Jackson et al. (2000) yields more accurate inclination values, while the declinations from our drift-corrected curve seem to better represent the local field evolution, at least for the first half of the century.
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D'Ajello Caracciolo, F., A. Pignatelli, F. Speranza, and A. Meloni. "A re-evaluation of the Italian historical geomagnetic catalogue: implications for paleomagnetic dating at active Italian volcanoes." Solid Earth 2, no. 1 (June 9, 2011): 65–74. http://dx.doi.org/10.5194/se-2-65-2011.
Full textAbstract:
Abstract. Paleomagnetism is proving to represent one of the most powerful dating tools of volcanics emplaced in Italy during the last few centuries/millennia. This method requires that valuable proxies of the local geomagnetic field (paleo)secular variation ((P)SV) are available. To this end, we re-evaluate the whole Italian geomagnetic directional dataset, consisting of 833 and 696 declination and inclination measurements, respectively, carried out since 1640 AD at several localities. All directions were relocated via the virtual geomagnetic pole method to Stromboli (38.8° N, 15.2° E), the rough centre of the active Italian volcanoes. For declination-only measurements, missing inclinations were derived (always by pole method) by French data (for period 1670–1789), and by nearby Italian sites/years (for periods 1640–1657 and 1790–1962). Using post-1825 declination values, we obtain a 0.46 ± 0.19° yr−1 westward drift of the geomagnetic field for Italy. The original observation years were modified, considering such drift value, to derive at a drift-corrected relocated dataset. Both datasets were found to be in substantial agreement with directions derived from the field models by Jackson et al. (2000) and Pavon-Carrasco et al. (2009). However, the drift-corrected dataset minimizes the differences between the Italian data and both field models, and eliminates a persistent 1.6° shift of 1933–1962 declination values from Castellaccio with respect to other nearly coeval Italian data. The relocated datasets were used to calculate two post-1640 Italian SV curves, with mean directions calculated every 30 and 10 years before and after 1790, respectively. The curve comparison suggests that both available field models yield the best available SV curve to perform paleomagnetic dating of 1600–1800 AD Italian volcanics, while the Italian drift-corrected curve is probably preferable for the 19th century. For the 20th century, the global model by Jackson et al. (2000) yields more accurate inclination values, while the declinations from our drift-corrected curve seem to better represent the local field evolution, at least for the first half of the century.
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Cartwright, Jessica, Christopher J. Banks, and Meric Srokosz. "Improved GNSS-R bi-static altimetry and independent digital elevation models of Greenland and Antarctica from TechDemoSat-1." Cryosphere 14, no. 6 (June 15, 2020): 1909–17. http://dx.doi.org/10.5194/tc-14-1909-2020.
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Abstract. Improved digital elevation models (DEMs) of the Antarctic and Greenland ice sheets are presented, which have been derived from Global Navigation Satellite Systems-Reflectometry (GNSS-R). This builds on a previous study (Cartwright et al., 2018) using GNSS-R to derive an Antarctic DEM but uses improved processing and an additional 13 months of measurements, totalling 46 months of data from the UK TechDemoSat-1 satellite. A median bias of under 10 m and root-mean-square errors (RMSEs) of under 53 m for the Antarctic and 166 m for Greenland are obtained, as compared to existing DEMs. The results represent, compared to the earlier study, a halving of the median bias to 9 m, an improvement in coverage of 18 %, and a 4 times higher spatial resolution (now gridded at 25 km). In addition, these are the first published satellite altimetry measurements of the region surrounding the South Pole. Comparisons south of 88∘ S yield RMSEs of less than 33 m when compared to NASA's Operation IceBridge measurements. Differences between DEMs are explored, the limitations of the technique are noted, and the future potential of GNSS-R for glacial ice studies is discussed.
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Lim, Jae-Hyeon, Geochul Jeong, Hyung-Woo Lee, Jae-Bum Lee, Jong-Seok Lim, and Chan-Bae Park. "Design and Analysis of the 45kW-Class Magnetic Geared Permanent Magnet Synchronous Motor for Traction of Tram Vehicles." Applied Sciences 11, no. 14 (July 9, 2021): 6360. http://dx.doi.org/10.3390/app11146360.
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The magnetic geared permanent magnet synchronous motor (MG-PMSM) is a PMSM that has two rotors with different rotation speeds and includes the function of magnetic gear. The design studies of the 45kW-class MG-PMSM are conducted for the application of the driving system for a tram. In this research, first, to derive the detailed model of the 45kW-class MG-PMSM for the tram, the analysis of the characteristics according to the stator winding method was performed. After selecting the winding method that can reduce the size of the MG-PMSM, two design topologies were applied to determine the number of stator poles, the number of outer rotor pole pieces, and the number of inner rotor poles of the MG-PMSM. A 45kW-class MG-PMSM detailed model was derived by applying a design topology that can minimize the size of the MG-PMSM, and it was confirmed that the required performance is satisfied through electromagnetic characteristics analysis. In addition, the 4.5kW-class small-scaled MG-PMSM prototype with concentrated winding was manufactured to verify the validity of the analytical model, and performance verification was performed.
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Marmottant, Philippe, Thierry Biben, and Sascha Hilgenfeldt. "Deformation and rupture of lipid vesicles in the strong shear flow generated by ultrasound-driven microbubbles." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 464, no. 2095 (March 25, 2008): 1781–800. http://dx.doi.org/10.1098/rspa.2007.0362.
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Considering the elastic response of the membrane of a lipid vesicle (artificial cell) in an arbitrary three-dimensional shear flow, we derive analytical predictions of vesicle shape and membrane tension for vesicles close to a spherical shape. Large amplitude deviations from sphericity are described using boundary integral numerical simulations. Two possible modes of vesicle rupture are found and compared favourably with experiments: (i) for large enough shear rates the tension locally exceeds a rupture threshold and a pore opens at the waist of the vesicle and (ii) for large elongations the local tension becomes negative, leading to buckling and tip formation near a pole of the vesicle. We experimentally check these predictions in the case of strong acoustic streaming flow generated near ultrasound-driven microbubbles, such as those used in medical applications.
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Folsom, C. P., D. Ó. Fionnagáin, L. Fossati, A. A. Vidotto, C. Moutou, P. Petit, D. Dragomir, and J. F. Donati. "Circumstellar environment of 55 Cancri." Astronomy & Astrophysics 633 (January 2020): A48. http://dx.doi.org/10.1051/0004-6361/201937186.
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Context. 55 Cancri hosts five known exoplanets, most notably the hot super-Earth 55 Cnc e, which is one of the hottest known transiting super-Earths. Aims. Because of the short orbital separation and host star brightness, 55 Cnc e provides one of the best opportunities for studying star-planet interactions (SPIs). We aim to understand possible SPIs in this system, which requires a detailed understanding of the stellar magnetic field and wind impinging on the planet. Methods. Using spectropolarimetric observations and Zeeman Doppler Imaging, we derived a map of the large-scale stellar magnetic field. We then simulated the stellar wind starting from the magnetic field map, using a 3D magneto-hydrodynamic model. Results. The map of the large-scale stellar magnetic field we derive has an average strength of 3.4 G. The field has a mostly dipolar geometry; the dipole is tilted by 90° with respect to the rotation axis and the dipolar strength is 5.8 G at the magnetic pole. The wind simulations based on this magnetic geometry lead us to conclude that 55 Cnc e orbits inside the Alfvén surface of the stellar wind, implying that effects from the planet on the wind can propagate back to the stellar surface and result in SPI.
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Piirola, V., A. Reiz, and G. V. Coyne. "Simultaneous Five Color (Ubvri) Polarimetry of EF Eri." International Astronomical Union Colloquium 93 (1987): 197–201. http://dx.doi.org/10.1017/s0252921100104865.
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AbstractWe present the first observations of the AM Her type object EF Eri where both the polarization and the photometric data are recorded simultaneously in five color bands (UBVRI). The position angle rotates strongly (~30° ) vs. wavelength from U to 1, probably due to Faraday rotation or due to fact that the polarized radiation seen in the different wavelength bands comes from different parts of the accretion region. The phase dependence of the position angle requires field and accretion geometry more complicated than a simple centered dipole and a second emitting region producing weaker intermediate pulses in the infrared seems to be present. We derive the value of the inclination of the system i = 55° ± 5° , the colatitude of the active pole βl = 38° ± 5° i and the second emitting region β2 = 115° ± 5° , both of which are nearly at the same longitude facing the main accretion stream.
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Lantz, Björn. "Where should Captain Scott's support parties have turned back?" Polar Record 54, no. 1 (January 2018): 76–78. http://dx.doi.org/10.1017/s0032247418000098.
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ABSTRACTCaptain Robert Falcon Scott's plan for the attempt to reach the South Pole during the Terra Nova Expedition was to use horses, motorised sledges and dog teams to lay depots on the Ross Ice Shelf to advance the effective starting point for the three man-hauling groups to the foot of the Beardmore Glacier. His idea was that two of the groups would turn back after two and four weeks, after depositing supplies for the final polar party to rely on during the return journey. In this paper, the logic of the mathematical ‘jeep problem’ is applied to derive the theoretically optimal points at which the support parties should have turned back in order to optimise the relationship between distance and consumption of supplies. The results show that, according to this model, Scott took both his support parties along too far, especially the last support party under Lieutenant E.R.G.R. ‘Teddy’ Evans.
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Bonsignore, A., G. Ferretti, and G. Magnani. "Coulomb Friction Limit Cycles in Elastic Positioning Systems." Journal of Dynamic Systems, Measurement, and Control 121, no. 2 (June 1, 1999): 298–301. http://dx.doi.org/10.1115/1.2802469.
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The state space control of a positioning system affected by torsional elasticity at the gearbox is considered, using a motor position transducer only. An output feedback, pole placement controller is used, with an additional integral action on the tracking error to cancel it at steady state. Both experiments and simulations point out that large oscillations may appear for some sets of closed-loop poles which yields, in contrast to stick-slip cycles, instantaneous motor velocity reversals. It is shown that such oscillations are induced by “pure” Coulomb friction. The period of the oscillations is predicted precisely following the Tsypkin’s relay control theory and also by the approximate describing function method. The latter also allows understanding of how oscillations depend on observer and feedback control design and on plant parameters; thus we are able to derive guidelines for the design of an oscillation free closed-loop system.
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Kneißel, B. "The Global Distribution of Zodiacal Dust." Symposium - International Astronomical Union 139 (1990): 231–32. http://dx.doi.org/10.1017/s0074180900240758.
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From visible or infrared brightness observations of the zodiacal light, a large variety of models of the three-dimensional structure of the zodiacal dust cloud has been proposed. To assess the reliability of these models, we must first investigate their fit to a selected set of observational data. The fit is best for bulge models, which have an appreciable density over the solar poles. Next, we check the orbital inclination distributions predicted by the various models. A comparison of these distributions with those of minor bodies in the solar system does not support the preference for bulge models, but instead supports polar hole models with a negligible density over the solar pole. These uncertainties of modelling have to be kept in mind when models are used to derive the brightness contribution of zodiacal light, particularly in the infrared, where the data base is still limited.
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Choi, S., Y. Wang, R. J. Salawitch, T. Canty, J. Joiner, T. Zeng, T. P. Kurosu, et al. "Analysis of satellite-derived Arctic tropospheric BrO columns in conjunction with aircraft measurements during ARCTAS and ARCPAC." Atmospheric Chemistry and Physics 12, no. 3 (February 1, 2012): 1255–85. http://dx.doi.org/10.5194/acp-12-1255-2012.
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Abstract. We derive tropospheric column BrO during the ARCTAS and ARCPAC field campaigns in spring 2008 using retrievals of total column BrO from the satellite UV nadir sensors OMI and GOME-2 using a radiative transfer model and stratospheric column BrO from a photochemical simulation. We conduct a comprehensive comparison of satellite-derived tropospheric BrO column to aircraft in-situ observations of BrO and related species. The aircraft profiles reveal that tropospheric BrO, when present during April 2008, was distributed over a broad range of altitudes rather than being confined to the planetary boundary layer (PBL). Perturbations to the total column resulting from tropospheric BrO are the same magnitude as perturbations due to longitudinal variations in the stratospheric component, so proper accounting of the stratospheric signal is essential for accurate determination of satellite-derived tropospheric BrO. We find reasonably good agreement between satellite-derived tropospheric BrO and columns found using aircraft in-situ BrO profiles, particularly when satellite radiances were obtained over bright surfaces (albedo >0.7), for solar zenith angle <80° and clear sky conditions. The rapid activation of BrO due to surface processes (the bromine explosion) is apparent in both the OMI and GOME-2 based tropospheric columns. The wide orbital swath of OMI allows examination of the evolution of tropospheric BrO on about hourly time intervals near the pole. Low surface pressure, strong wind, and high PBL height are associated with an observed BrO activation event, supporting the notion of bromine activation by high winds over snow.
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Asiedu, Berchie. "The performance of tuna processing fishery sector to sustainable fish trade and food security in Ghana." Journal of Energy and Natural Resource Management 2, no. 1 (February 21, 2018): 8–14. http://dx.doi.org/10.26796/jenrm.v2i0.39.
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The paper presents an analysis of the performance of the tuna processing fishery sector of Ghana in order to derive the maximumbenefits for the Ghanaian economy. Interviews and document analysis were carried out with approved tuna processing firms,government institutions and statistical service of the European Union. Results showed that the Ghanaian tuna processing industryis mainly supplied with raw material coming from national vessels, both purse seiners and pole and line. This raw material is onlyenough to have the plants operating at 60% of their maximum capacity. There are a total of 6, 500 people employed in the tunafish chain. A total of 58, 000 tonnes of tuna is canned annually. The market destinations are Europe, National and Ivory Coast,ranked in a descending order according to the tonnage. In conclusion, Ghana has huge potential to increase tuna fish exportand can generate more economic and social benefits, such as food security, employment, foreign exchange, income and povertyreduction to the Ghanaian economy.
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VAN TONDER, ANDRÉ, and MIQUEL DORCA. "NONPERTURBATIVE QUANTIZATION OF PHANTOM AND GHOST THEORIES: RELATING DEFINITE AND INDEFINITE REPRESENTATIONS." International Journal of Modern Physics A 22, no. 14n15 (June 20, 2007): 2563–608. http://dx.doi.org/10.1142/s0217751x07036580.
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We investigate the nonperturbative quantization of phantom and ghost degrees of freedom by relating their representations in definite and indefinite inner product spaces. For a large class of potentials, we argue that the same physical information can be extracted from either representation. We provide a definition of the path integral for these theories, even in cases where the integrand may be exponentially unbounded, thereby removing some previous obstacles to their nonperturbative study. We apply our results to the study of ghost fields of Pauli–Villars and Lee–Wick type, and we show in the context of a toy model how to derive, from an exact nonperturbative path integral calculation, previously ad hoc prescriptions for Feynman diagram contour integrals in the presence of complex energies. We point out that the pole prescriptions obtained in ghost theories are opposite to what would have been expected if one had added conventional i∊ convergence factors in the path integral.
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Vondrák, J., and C. Ron. "Earth orientation and its excitations by atmosphere, oceans, and geomagnetic jerks." Serbian Astronomical Journal, no. 191 (2015): 59–66. http://dx.doi.org/10.2298/saj1591059v.
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In addition to torques exerted by the Moon, Sun, and planets, changes of the Earth orientation parameters (EOP) are known to be caused also by excitations by the atmosphere and oceans. Recently appeared studies, hinting that geomagnetic jerks (GMJ, rapid changes of geomagnetic field) might be associated with sudden changes of phase and amplitude of EOP (Holme and de Viron 2005, 2013, Gibert and Le Mou?l 2008, Malkin 2013). We (Ron et al. 2015) used additional excitations applied at the epochs of GMJ to derive its influence on motion of the spin axis of the Earth in space (precession-nutation). We demonstrated that this effect, if combined with the influence of the atmosphere and oceans, improves substantially the agreement with celestial pole offsets observed by Very Long-Baseline Interferometry. Here we concentrate our efforts to study possible influence of GMJ on temporal changes of all five Earth orientation parameters defining the complete Earth orientation in space. Numerical integration of Brzezi?ski's broad-band Liouville equations (Brzezi?ski 1994) with atmospheric and oceanic excitations, combined with expected GMJ effects, is used to derive EOP and compare them with their observed values. We demonstrate that the agreement between all five Earth orientation parameters integrated by this method and those observed by space geodesy is improved substantially if the influence of additional excitations at GMJ epochs is added to excitations by the atmosphere and oceans.
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González, J. F., M. Briquet, N. Przybilla, M. F. Nieva, P. De Cat, S. Saesen, S. Hubrig, et al. "HD 96446: a long-period binary with a strongly magnetic He-rich primary with β Cephei pulsations." Astronomy & Astrophysics 626 (June 2019): A94. http://dx.doi.org/10.1051/0004-6361/201935177.
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Aims. HD 96446 is a magnetic B2p He-strong star that has been reported to be a β Cep pulsator. We present a detailed spectroscopic analysis of this object based on an intensive observational data set obtained in a multisite campaign with the spectrographs CORALIE, FEROS, and HARPS (La Silla); UVES (Paranal); HERCULES (Mt. John Observatory); and GIRAFFE (SAAO). Methods. Radial velocities were measured by cross-correlations and analysed to detect periodic variations. On the other hand, the mean spectrum was fit with spectral synthesis to derive atmospheric parameters and chemical abundances. Results. From the analysis of radial velocities, HD 96446 was found to be a spectroscopic binary with a period of 799 days. The stellar companion, which contributes only ∼5% of the total flux, is an A0-type star. A frequency analysis of the radial velocities allowed us to detect two pulsational modes with periods 2.23 h and 2.66 h. The main mode is most probably a low-inclination, dipole mode (l, m) = (1, 0), and the second pulsation mode corresponds to (l, m) = (2, 2) or to a pole-on (l, m) = (3, 2) configuration. In addition to radial velocities, the main pulsation mode is evidenced through small variations in the spectral morphology (temperature variations) and the light flux. The rotation period of 23.4 d, was detected through the variation in line intensities. Chemical abundances are unevenly distributed over the stellar surface, with helium concentrated at the negative magnetic pole and most metals strengthened at lower latitudes. The mean chemical abundance of helium is strongly abnormal, reaching a value of 0.60 (number fraction).
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Belov, A. V., E. A. Eroshenko, B. Heber, V. G. Yanke, A. Raviart, R. Müller-Mellin, and H. Kunow. "Latitudinal and radial variation of >2 GeV/n protons and alpha-particles at solar maximum: ULYSSES COSPIN/KET and neutron monitor network observations." Annales Geophysicae 21, no. 6 (June 30, 2003): 1295–302. http://dx.doi.org/10.5194/angeo-21-1295-2003.
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Abstract. Ulysses, launched in October 1990, began its second out-of-ecliptic orbit in September 1997. In 2000/2001 the spacecraft passed from the south to the north polar regions of the Sun in the inner heliosphere. In contrast to the first rapid pole to pole passage in 1994/1995 close to solar minimum, Ulysses experiences now solar maximum conditions. The Kiel Electron Telescope (KET) measures also protons and alpha-particles in the energy range from 5 MeV/n to >2 GeV/n. To derive radial and latitudinal gradients for >2 GeV/n protons and alpha-particles, data from the Chicago instrument on board IMP-8 and the neutron monitor network have been used to determine the corresponding time profiles at Earth. We obtain a spatial distribution at solar maximum which differs greatly from the solar minimum distribution. A steady-state approximation, which was characterized by a small radial and significant latitudinal gradient at solar minimum, was interchanged with a highly variable one with a large radial and a small – consistent with zero – latitudinal gradient. A significant deviation from a spherically symmetric cosmic ray distribution following the reversal of the solar magnetic field in 2000/2001 has not been observed yet. A small deviation has only been observed at northern polar regions, showing an excess of particles instead of the expected depression. This indicates that the reconfiguration of the heliospheric magnetic field, caused by the reappearance of the northern polar coronal hole, starts dominating the modulation of galactic cosmic rays already at solar maximum.Key words. Interplanetary physics (cosmic rays; energetic particles) – Space plasma physics (charged particle motion and acceleration)
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Yahagi, Shuichi, and Itsuro Kajiwara. "Direct tuning of the data-driven controller considering closed-loop stability based on a fictitious reference signal." Measurement and Control 54, no. 5-6 (April 29, 2021): 1026–42. http://dx.doi.org/10.1177/00202940211010834.
Full textAbstract:
The direct tuning of controller parameters, which is based on data-driven control, has been attracting considerable attention because of the ease of its control system design. In practical use, it is important to consider the stability of the closed-loop system and model matching with few design parameters. In this study, we propose a direct tuning method based on a fictitious reference signal that considers the bounded-input bounded-output (BIBO) and model matching without repeating experiments. The proposed method includes two steps. In the first step, the BIBO stability is satisfied. The pole information is lost in the cost function of the conventional method using a fictitious reference signal. Then, we derive a new cost function that can prevent the loss of the pole information. This provides controller parameters that can stabilize the closed-loop system. The model matching between the reference model and the closed-loop system is considered in the second step. When model matching is achieved, the characteristics of the reference model almost match those of the closed-loop system, including the gain and phase margins. The parameters of the reference model are automatically tuned to realize model matching. Using the two-step method, we can obtain parameters considering BIBO stability and the model matching. In addition, there are no design parameters apart from the dealing noise. Two simulations and an experiment were performed on a system with dead time to verify the effectiveness of the proposed two-step method. The results showed that the proposed method provides BIBO stability and model-matched control parameters from the measured data through a one-time experiment without trial and error.
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Xie, Chuan, Ling Ling He, and Bing Lin. "Research and Design of a Spatial Attitude Measurement System for Drilling Tools." Advanced Materials Research 361-363 (October 2011): 353–59. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.353.
Full textAbstract:
Autonomous navigation research in the process of drilling has been a very challenging advanced topic and it requires the drill pole must adjust their own space attitude before the directional move. Strapdown inertial navigation has an explicit definition of the space attitude information which will be reflected by the inclination, the azimuth angle and the tool face angle specifically. For the defect in the open mathematical model solver of the spatial attitude information, we derive another mathematical model of the inclination, the magnetic azimuth angle and the tool face angle with the space coordinates transformation, the spatial straight line equation and the dog-leg angle’s definition and give the specific achievable plan by making use of the triple-axis accelerometer and the triple-axis magnetometer. The experimental result indicated that this plan can get the correct spatial attitude within ±0.1º error to the inclination and ±1.5º error to magnetic azimuth angle and the tool face angle. In addition, its cost is very low and the volume is very small, so it is really an ideal choice for the spatial attitude measurement system.
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Soldin, Dennis. "Atmospheric Muons Measured with IceCube." EPJ Web of Conferences 208 (2019): 08007. http://dx.doi.org/10.1051/epjconf/201920808007.
Full textAbstract:
IceCube is a cubic-kilometer Cherenkov detector in the deep ice at the geographic South Pole. The dominant event yield is produced by penetrating atmospheric muons with energies above several 100 GeV. Due to its large detector volume, IceCube provides unique opportunities to study atmospheric muons with large statistics in detail. Measurements of the energy spectrum and the lateral separation distribution of muons offer insights into hadronic interactions during the air shower development and can be used to test hadronic models. We will present an overview of various measurements of atmospheric muons in IceCube, including the energy spectrum of muons between 10 TeV and 1 PeV. This is used to derive an estimate of the prompt contribution of muons, originating from the decay of heavy (mainly charmed) hadrons and unflavored mesons. We will also present measurements of the lateral separation distributions of TeV muons between 150m and 450m for several initial cosmic ray energies between 1 PeV and 16 PeV. Finally, the angular distribution of atmospheric muons in IceCube will be discussed.
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Sommer, Tobias, Jeffrey R. Carpenter, Martin Schmid, Rolf G. Lueck, and Alfred Wüest. "Revisiting Microstructure Sensor Responses with Implications for Double-Diffusive Fluxes." Journal of Atmospheric and Oceanic Technology 30, no. 8 (August 1, 2013): 1907–23. http://dx.doi.org/10.1175/jtech-d-12-00272.1.
Full textAbstract:
Abstract Thin high-gradient interfaces that occur naturally within double-diffusive staircases are used to estimate the response characteristics of temperature and conductivity microstructure sensors. The knowledge of these responses is essential for resolving small-scale turbulence in natural water bodies and for determining double-diffusive fluxes of heat and salt. Here, the authors derive microstructure sensor responses from observed differences in the statistical distributions of interface thicknesses at various profiling speeds in Lake Kivu (central Africa). In contrast to the standard approach for determining sensor responses, this method is independent of any knowledge of the true in situ temperature and salinity structure. Assuming double-pole frequency response functions, the time constants for the Sea-Bird Electronics SBE-7 conductivity sensor and the Rockland Scientific International FP07 thermistor are estimated to be 2.2 and 10 ms, respectively. In contrast to previous assumptions, the frequency response for the SBE-7 is found to be substantial and dominates the wavenumber response for profiling speeds larger than 0.19 m s−1.