Full Pole Research Articles

Effect of kiln drying schedule on the quality of South African grown Eucalyptus grandis poles

In specific cases, kiln drying prior to preservative treatment is the prescribed method of utility pole seasoning in South Africa. The slow drying nature of Eucalyptus grandis poles makes rapid kiln drying potentially detrimental due to development of defects such as excessive surface checking, honeycomb and collapse. To control these defects while maintaining the fastest drying rate possible, the effect of drying schedule on the drying quality of E. grandis poles was investigated. Full length pole drying was simulated in thirty 2.1 m long butt sections of poles of which the top ends were end sealed. Three industrially used schedules that differed in dry and wet bulb temperature and duration of drying (Tdb, Twb and time) were chosen: 80°C/59°C/8 days, 80°C/69°C/10 days and 70°C/59°C/12 days. Surface check length of each pole was measured after drying. Cross-sections cut at the theoretical ground line (TGL), 1.5 m from the butt end, were used to measure the moisture content (MC) gradient between the shell and core of poles. Digital image analysis of cross-sections of discs cut at TGL was used to measure the area of honeycomb and disc cross-section. Collapse was assessed qualitatively.

Active Control of Flow-Induced Vibrations via Feedback Decoupling

This paper deals with the flutter instability characteristics of a cantilever pipe conveying fluid flow, and explores the applicability of an active nodal vibration control for suppressing the associated structural vibration. The Euler-Bernoulli theory is used to represent pipe bending. The finite element method is used to discretize the governing equation. The control law is based on full state feedback and pole assignment, and requires as many actuators as the number of nodal degrees-of-freedom. Considering that this is not practical, a reduced order model with less number of elements is used to design the controller, and the resulting control input is applied to the “full” or the “truth” model. In this case, since the feedback simplification will not be complete, some performance degradation is to be expected. It is however demonstrated that the proposed control strategy can ensure closed loop stability for a wide range of flow velocity even if the critical flow velocity is exceeded. The effectiveness of the proposed method, in damping out the pipe vibrations, is also demonstrated clearly by comparing its results with those obtained by a direct velocity feedback control which is equivalent to add an external viscous damper to the pipe. The proposed control is essentially a model-based controller, and hence suffers from modeling errors and uncertainties in model parameters. Therefore, the robustness of the control is also investigated. It is shown that the proposed controller significantly reduces sensitivity of the uncontrolled system to flow conditions. It works effectively to suppress the vibrations of a fluid conveying cantilever pipe due to any disturbance.

Lead-free piezoelectric ceramics based on perovskite structures

The piezoelectric properties of a solid solution based on three components of bismuth sodium titanate (Bi1/2Na1/2)TiO3 (BNT), bismuth potassium titanate, (Bi1/2K1/2)TiO3 (BKT), and barium titanate, BaTiO3 (BT), that is x(Bi1/2Na1/2)TiO3−y(Bi1/2K1/2)TiO3−zBaTiO3, [ $$ x + y + z = 1 $$ , abbreviated as BNBKy:z(x)] and potassium niobate, KNbO3 (KN) based ceramics, that is KN+MnCO3 x wt.%, [abbreviated as KN−Mn x], were studied as a lead-free piezoelectric material. In the case of BNBK2:1 system, high piezoelectric properties were obtained near the MPB composition, and the highest electromechanical coupling factor, k 33 and piezoelectric constant, d 33, were 0.58 for BNBK2:1(0.89) and 181 pC/N for BNBK2:1(0.88). Nevertheless, the depolarization temperature, T d , shifts to lower temperature around the MPB compositions, and the T d ’s of BNBK2:1(0.88–0.90) are only about 100 °C. On the tetragonal side, the T d shifts to higher temperature with increasing the lattice anisotropy, c/a. As T d higher than 200 °C was obtained in the range of x < 0.78, with a k 33 and d 33 for BNBK2:1(0.78) being 0.45 and 128 pC/N, respectively. In the case of Mn doped KN ceramics, dense and non deliquescence KN ceramic were successfully obtained via ordinary firing technique in air by optimizing the fabrication process. Mn doping for KN ceramics was effective to obtain full poling state easily under poling conditions of high temperature and high electric field. As a result, we obtained the excellent piezoelectric properties of k 33 = 0.507 for KN−Mn0.2.

Crystallographic Texture and Whiskers in Electrodeposited Tin Films

Electron back scatter diffraction (EBSD) analysis was used to determine texture for electrodeposited tin films, and the results were compared to standard X-ray "times random" and full pole figure texture analysis. The data showed that EBSD and X-ray texture results differed as to primary and secondary texture determinations with some degree of correlation between texture determinations when primary/secondary/tertiary calculations were disregarded. It is these authors' opinion that film texture cannot be accurately determined using "times random" X-ray diffraction (XRD) techniques, and that there is considerable room for error with X-ray pole figure analyses. These data must be considered preliminary due to the small sample size, but these results indicate that electroplaters may have better control over as-deposited tin film texture than is currently believed, and that there is a relationship between as-deposited texture and film stress

Calculation of the flux-linkage characteristics of a switched reluctance motor by flux tube method

The torque developed by a switched reluctance motor (SRM) is dependent on the change of flux-linkage and rotor position. The flux-linkage is a function of both the excitation and the rotor position. Due to the nonlinear nature of this motor, estimation of the flux-linkage characteristics is cumbersome. In this paper, a simple analytical method to estimate the flux-linkage characteristics of SRM is presented. Here, equations for the calculation of inductance and the flux-linkage for three identified regions based on the rotor position; a) fully unaligned to starting of pole overlap, b) starting of pole overlap to full pole overlap, and c) full pole overlap to fully aligned conditions, are derived in terms of motor dimensions, the magnetic properties of the materials used, and the stator excitation. The validation of the results obtained from this new analytical method is carried out using the finite element analysis of the motors.

Structure, Deformation, and Failure of Flow-Oriented Semicrystalline Polymers

This study deals with the influence of processing induced crystalline orientation on the macroscopic deformation and failure behavior of thin samples of polyethylene and polypropylene. Distribution and structure of flow-induced orientations were characterized by optical microscopy, X-ray diffraction techniques, and transmission electron microscopy. Hermans' orientation functions were either determined from the flat plate wide-angle X-ray diffraction patterns or calculated from full pole figures. The deformation behavior of the oriented samples was studied in both impact and tensile testing conditions and was found to be strongly anisotropic and related to the oriented structure. For all polymers studied, an increase of extended chains (shish) in the loading direction is proposed to cause an increase in the yield stress, and a lamellar structure oriented perpendicular to loading direction leads to an increase in strain hardening. In the extruded samples, where a low level of extended chains and a high level of oriented lamellae were found, the resulting combination of yield stress and strain hardening leads to homogeneous deformation. Brittle−ductile transitions in impact toughness of the molded samples could also be explained from differences in yield stress and strain hardening. Toughness enhancement was found to be most efficient with increasing strain hardening, and the effect was less pronounced in the polypropylene samples.

Texture Measurement in Zr-2.5%Nb Pressure Tubes for Pressurized Heavy Water Reactors

Abstract Preferred orientation or crystallographic texture of Zr-2.5%Nb pressure tubes for a pressurized heavy water reactor (PHWR) affects all the critical in-reactor properties. The preferred orientation has to be measured to standardize the process route for getting the desired in-reactor properties. The quantitative determination involves determination of the complete pole figure and calculation of Kearns parameters from the pole figure data. Independently, neither the X-ray reflection nor the X-ray transmission technique can provide the full pole figure data. The literature reports only partial pole figures. Quantification of texture based on partial pole figures may lead to errors in estimation. For a complete pole figure determination, it is required to merge the data from both the reflection and the transmission techniques. This requires a special test setup that can combine the pole figure data obtained from the two techniques. In this paper, a methodology for determination of the complete pole figure with quantitative texture parameters for Zr-2.5%Nb pressure tubes is reported.

Renormalization in Quantum Field Theory and the Riemann--Hilbert Problem II: The β-Function, Diffeomorphisms and the Renormalization Group

We showed in part I (hep-th/9912092) that the Hopf algebra ${\cal H}$ of Feynman graphs in a given QFT is the algebra of coordinates on a complex infinite dimensional Lie group $G$ and that the renormalized theory is obtained from the unrenormalized one by evaluating at $\ve=0$ the holomorphic part $\gamma_+(\ve)$ of the Riemann-Hilbert decomposition $\gamma_-(\ve)^{-1}\gamma_+(\ve)$ of the loop $\gamma(\ve)\in G$ provided by dimensional regularization. We show in this paper that the group $G$ acts naturally on the complex space $X$ of dimensionless coupling constants of the theory. More precisely, the formula $g_0=gZ_1Z_3^{-3/2}$ for the effective coupling constant, when viewed as a formal power series, does define a Hopf algebra homomorphism between the Hopf algebra of coordinates on the group of formal diffeomorphisms to the Hopf algebra ${\cal H}$. This allows first of all to read off directly, without using the group $G$, the bare coupling constant and the renormalized one from the Riemann-Hilbert decomposition of the unrenormalized effective coupling constant viewed as a loop of formal diffeomorphisms. This shows that renormalization is intimately related with the theory of non-linear complex bundles on the Riemann sphere of the dimensional regularization parameter $\ve$. It also allows to lift both the renormalization group and the $\beta$-function as the asymptotic scaling in the group $G$. This exploits the full power of the Riemann-Hilbert decomposition together with the invariance of $\gamma_-(\ve)$ under a change of unit of mass. This not only gives a conceptual proof of the existence of the renormalization group but also delivers a scattering formula in the group $G$ for the full higher pole structure of minimal subtracted counterterms in terms of the residue.

Reduction mammaplasty and mastopexy with shorter scar and better shape

Background: Efforts to reduce the size or improve the shape of the ptotic breast have resulted in long, obtrusive scars or a shape that lacks upper-pole fullness and projection. Objective: The goal of the present study was to evaluate the short-term and long-term results of a modified procedure that was designed to provide long-lasting upper-pole fullness and reduce visible scarring. Methods: As a result of the use of a shortened oblique incision and the elevation of an inferior chest wall-based flap, divided at its inferior subcutaneous attachment and maintained in the cephalad position by a loop of pectoral muscle, the scar is unobtrusive and the shape is optimal, with lasting fullness in the upper pole. Results: From 1984 to 1998, 1521 women underwent breast reduction or mastopexy. Long-term follow-up (4 years) indicates maintenance of the full upper pole of the breast and satisfaction of nearly all of the patients. All complications, which included steatonecrosis and skin dehiscence below the areola, resolved without additional surgery within 6 months postoperatively. Conclusions: An aesthetically pleasing breast requires a proper shape and adequate skin cover, with a nipple-areola complex at the apex of the mound. The technique presented achieves these goals with an unobtrusive lateral scar that does not extend beyond the anterior axillary line.

Crystallographic texture of C54 titanium disilicide as a function of deep submicron structure geometry

Detailed analysis of the crystallographic texture of C54 TiSi2 was performed and showed a strong correlation between the geometry of the silicide structures and preferential crystallographic orientation. The study was undertaken on blanket and patterned TiSi2 films formed in the reaction between 32 nm of Ti and undoped polycrystalline silicon using both in situ x-ray diffraction during heating and post-anneal four-circle pole figure reflection geometry measurements. Full pole figures were taken to determine the distribution of C54 TiSi2 grain orientations in narrow (0.2 to 1.1 μm) lines which was compared with similar results obtained from unpatterned (blanket) films. While in blanket films we found the presence of weak C54 TiSi2 crystallographic orientation perpendicular to the sample surface, the preferential orientation dominated in patterned submicron line structures and increased with decreasing linewidth. Using pole figure analysis, we observed strong fiber texture in narrow lines with a slight variation in the tilt of the (040) planes normal in the direction perpendicular to the line (full width at half maximum [FWHM] ≈6°), but very little along the length of the line (FWHM ≈2°). In addition, a preferred in-plane (azimuthal) orientation of crystals was found which showed that most of the grains had their (004) plane normals oriented parallel with the line direction. These findings support a model of the C49 to C54 TiSi2 transformation involving rapid growth of certain orientations favored by the one-dimensional geometry imposed by narrow lines.

A 1.8 T permanent magnet wiggler for MAX-lab

The design and construction of a permanent magnet wiggler for generation of soft X-rays at the new 1.5 GeV electron storage ring MAX II in MAX-lab, Lund, Sweden is reported. The 2.65 meters long device has 27 full field poles with a peak field of 1.8 tesla, which produce a total power of 2.2 kW of soft X-rays (up to 15 keV photon energy) at the nominal beam current of 200 mA. The device was installed in the MAX II storage ring in 1994, to serve in the commissioning phase of the accelerator. The corresponding beamline should become operational in 1996.

A 3D finite-element computation of eddy currents and losses in the stator end laminations of large synchronous machines

Eddy current losses due to axial fluxes are computed in the stator end laminations of a salient-pole synchronous machine under open-circuit operating conditions. The calculation is carried out with the aid of a 3D finite-element package which uses a linear T-/spl phi/ formulation. The domain spans a full pole pitch of the machine. The flux densities computed in the end region at points outside the stator core are compared with experimental measurements. The results and the limitations of the model are discussed.

Elliptical multipole wiggler facility at the Advanced Photon Source

The use of circularly polarized radiation is advantageous for the study of magnetic materials using x-ray scattering techniques. The APS is an ideal source of x-ray radiation for such studies. We present a description of the elliptical multipole wiggler (EMW) [S. Yamamoto, H. Kawata, H. Kitamura, and M. Ando, Phys. Rev. Lett. 62, 2672 (1989)] to be constructed at the APS. This device has been chosen for reasons of tunability and special polarization properties. This insertion device is capable of producing circularly polarized x rays on axis. The EMW period will be λu=16 cm, the number of full strength poles in the hybrid structure is 31, and the device length is 2.8 m. The hybrid magnetic structure produces a peak vertical magnetic field with Ky=14 and the electromagnet provides horizontal magnetic field with Kx=1–2. The frequency of the horizontal field change is up to 10 Hz. The beamline will consist of three stations operating in tandem with only one station receiving x rays at any one time. The three stations have three distinct functions, namely Compton scattering, magnetic scattering, and surface scattering. Special considerations will be made to insure the proper control of the polarization when using circular polarized light. The design of the elliptical multipole wiggler beam line will follow an approach very close to that developed by Kawata et al. [Rev. Sci. Instrum. 60, 1885 (1989)]. Our objective is to obtain a high photon flux with energies above 40 keV and well characterized polarization.

Nonleptonic charmed-baryon decays: Symmetry properties of parity-violating amplitudes

We study the effects of pole-model-induced SU(4)-symmetry breaking in parity-violating amplitudes of Cabibbo-favored nonleptonic decays of charmed baryons. A simple technique generalizing the expressions of current algebra to the case of flavor symmetry breaking in the intermediate state is applied to sum the contributions from all intermediate excited 1/${2}^{\mathrm{\ensuremath{-}}}$ baryons of a given charm. The technique permits easy discussion of departures from current algebra for any values of \ensuremath{\Delta}c/\ensuremath{\Delta}\ensuremath{\omega} (\ensuremath{\Delta}c is the charm-noncharm mass difference, \ensuremath{\Delta}\ensuremath{\omega} the 1/${2}^{\mathrm{\ensuremath{-}}}$-1/${2}^{+}$ mass difference). We find that in the pole model the symmetry structure of parity-violating amplitudes of charmed-baryon decays into an octet baryon and an octet pseudoscalar meson consists of two pieces: (i) a term proportional to the standard current algebra expression but much smaller and of opposite sign and (ii) a term proportional to the factorization contribution, interfering with it destructively. The symmetry structure of parity-violating amplitudes for decays with vector meson production is also given. We apply the full pole model to the description of available data, compare it with the results of current algebra, and indicate places where a good discrimination between the pole model and current algebra should be possible.

Determination of the orientation distribution function from arbitrary pole figure regions

A full pole figure is required to calculate the series expansion coefficients of the pole figure, by integration. The orientation distribution function (ODF) is then calculated by solving a system of linear equations relating the coefficients of the pole figures and those of the ODF. Using a method proposed by Bunge which does not require integration at all, but assuming a fit between the theoretical ODF and the isolated experimental points, we calculated the ODF from various arbitrary chosen regions of the pole figures. This technique was applied to analyse the experimental data obtained from the measurement of three, two and one pole figures. Various tests described in this paper allow us to suggest an empirical rule indicating that the number of experimental data points should be three times higher than the number of required series expansion coefficients of the ODF.

A 2-MV 4.5-MJ Synthetic Test Source for HV Circuit Breakers

This paper describes IREQ's synthetic test source, which underwent commissioning tests in July 1983. Its unusual physical and electrical characteristics are given along with a description of its fully computerized operation. This source has already been used for six different types of test. Tests on full poles of 735-kV circuit breakers as well as on metal-oxide surge arrester sections intended for a 735-kV transmission system were performed.

Wiggler magnets at SSRL-present experience and future plans

A wiggler magnet has been installed in SPEAR and has been routinely used asa radiation source for Beam Line IV at SSRL since March, 1979. The magnet is 1.22 m long. It has five full central poles and two end half-poles producing a total of three complete small amplitude (⩽1 mm) oscillations of the electron beam in traversing the magnet. The magnet has been operated with the peak field in the central full poles at 17.2 kG and produces an intense beam of synchrotron radiation extending to 12 keV and beyond even at the lowest operating energies of SPEAR (1.5 GeV). It is compatible with all phases of colliding-beam operation of SPEAR and has improved the colliding-beam luminosity. The results of measurements on the spectrum and intensity of the radiation produced by the Wiggler will be presented. The measured effects of the wiggler on the stored beam tunes, energy spread and emittance will also be presented. Plans will also be described for installing additional high field wiggler magnets in SPEAR and also weak-field, many-period undulator magnets in both SPEAR and PEP.

PEP Insertion Quadrupole Design Features

The insertion quadrupoles for the PEP storage ring must have a very uniform gradient to focus the circulating beams to a very small size at the interaction point for high luminosity. Quads have been built which achieve the desired field within the full pole aperture radius to approximately one part in 104. The design features which permitted this achievement are described.

Status Report on the Wiggler Magnet for Adone

A 1.9 Tesla, 6 full poles wiggler magnet, decreasing the critical wavelength of synchrotron radiation in Adone from 8.3 A to 4.4 A has been built in the Frascati National Laboratories. The results of the first measurements are presented.

An Experimental Study of Induction Machine End-Turn Leakage Reactance

There are a number of empirical and rationally derived methods described in the technical literature for the predetermination of the end-turn leakage reactance of an induction machine stator winding. The use of these calculation methods will yield widely different results when applied to a particular machine winding. Since the isolation of the end-turn leakage reactance from test results requires extensive and tedious experimental work, the designer seldom, if ever, has the opportunity to verify the accuracy of the calculation method which he uses. It is the object of the subject study to determine experimentally the actual endturn leakage reactance for a limited size range and variety of 3-phase squirrel-cage induction motor winding conditions. The experimental data are used to evaluate the relative accuracy of several published calculation methods, and to suggest refinements in one of these methods which will permit attainment of practical degrees of accuracy in design calculations. An empirical calculation method published by Alexander Gray is found to be more accurate in its predictions for the range of machine sizes involved than any of the other methods considered, however, it is limited to use with stator windings having only full pole pitch coils. Since modern design practice dictates, from several considerations, the use of fractional pitch coils, it is necessary to develop additional empirical data to enable calculation of end-turn leakage reactance for this condition.