Field oriented control of induction motors

Induction motors have always been known for their simple rugged construction, but until lately were not suitable for variable speed or servo drives due to the inherent complexity of the controls. With the advent of field oriented control (FOC), however, the induction motor has become an attractive option for these types of drive systems. An FOC system which utilizes the pulse population modulation method to synthesize the motor drive frequencies is examined. This system allows for a variable voltage to frequency ratio and enables the user to have independent control of both the speed and torque of an induction motor. A second generation of the control boards were developed and tested with the next point of focus being the minimization of the size and complexity of these controls. Many options were considered with the best approach being the use of a digital signal processor (DSP) due to its inherent ability to quickly evaluate control algorithms. The present test results of the system and the status of the optimization process using a DSP are discussed

Reconstruction of the two-dimensional gravitational potential of galaxy clusters from X-ray and Sunyaev-Zel'dovich measurements

The mass of galaxy clusters is not a direct observable, nonetheless it is commonly used to probe cosmological models. Based on the combination of all main cluster observables, that is, the X-ray emission, the thermal Sunyaev-Zel'dovich (SZ) signal, the velocity dispersion of the cluster galaxies, and gravitational lensing, the gravitational potential of galaxy clusters can be jointly reconstructed. We derive the two main ingredients required for this joint reconstruction: the potentials individually reconstructed from the observables and their covariance matrices, which act as a weight in the joint reconstruction. We show here the method to derive these quantities. The result of the joint reconstruction applied to a real cluster will be discussed in a forthcoming paper. We apply the Richardson-Lucy deprojection algorithm to data on a two-dimensional (2D) grid. We first test the 2D deprojection algorithm on a $\beta$-profile. Assuming hydrostatic equilibrium, we further reconstruct the gravitational potential of a simulated galaxy cluster based on synthetic SZ and X-ray data. We then reconstruct the projected gravitational potential of the massive and dynamically active cluster Abell 2142, based on the X-ray observations collected with XMM-Newton and the SZ observations from the Planck satellite. Finally, we compute the covariance matrix of the projected reconstructed potential of the cluster Abell 2142 based on the X-ray measurements collected with XMM-Newton. The gravitational potentials of the simulated cluster recovered from synthetic X-ray and SZ data are consistent, even though the potential reconstructed from X-rays shows larger deviations from the true potential. Regarding Abell 2142, the projected gravitational cluster potentials recovered from SZ and X-ray data reproduce well the projected potential inferred from gravitational-lensing observations. (abridged)Comment: accepted for publication in the journal A&

New insights from U–Pb zircon dating of Early Ordovician magmatism on

The Central Iberian–Ossa-Morena transition zone (SW Iberian Massif) represents a segment of the northern Gondwana margin with a long geodynamic evolution, characterized by the superposition of Cadomian and Variscan events. The Early Ordovician is mainly represented by porphyritic felsic volcaniclastic rocks (the Urra Formation) that pass up into a siliciclastic sediments typical of the Central Iberian Zone (Lower Ordovician Armorican Quartzite Formation). The Urra Formation unconformably overlies the previously deformed and metamorphosed Ediacaran sediments of the Série Negra (with Ossa-Morena Zone paleogeographic affinity). New SHRIMP zircon data obtained from the Urra Formation volcaniclastic rocks indicate an Early Ordovician age (206Pb/238U ages ranging from 494.6±6.8 Ma to 488.3±5.2 Ma) for this magmatic event. The inherited zircon cores indicate the presence of multicycle protoliths with different Precambrian ages: Neoproterozoic (698–577 Ma), Paleoproterozoic (2.33 Ga) and Paleoarchean (3.2–3.3 Ga). There is a noticeable lack of Meso- to Neoarchean and Mesoproterozoic ages. The data support the hypothesis that the volcaniclastic rocks were derived by partial melting of Cadomian basement (linked to a West African Craton provenance). The Urra Formation volcaniclastic rocks have rhyolitic to dacitic compositions, are peraluminous and similar to calc-alkaline high-K series suites elsewhere. Isotopic signatures present a wide range of values (87Sr/86Sr)t=0.7085–0.7190, more restricted εNdt (−2.65 to −0.35) and δ18O=9.63–10.34‰, compatible with magmas derived from crustal rocks, including portions of the lower crust. Some samples show disturbance of the Rb–Sr system as shown by unrealistic values for (87Sr/86Sr)tb0.703, probably due to Variscan deformation and metamorphism. The volcaniclastic rocks with a significant sedimentary contribution (upper unit) are distinguished from the others by the lowest values of εNdt (−5.53 to −4.85). The geochemical data are compatible with an orogenic geodynamic environment. However, the “orogenic” signature can be considered to represent, in part, an inherited feature caused by melting of the Cadomian basement which also has calc-alkaline affinities. The Early Ordovician crustal growth and associated magmatism, represented by the Urra felsic volcaniclastic rocks and associated calc-alkaline granitoids, diorites and gabbros, can be interpreted in terms of the underplating and temporal storage of mantle-derived magmas as the potential source for the “orogenic melts” that were intruded during Early Paleozoic extension. This record of Early Ordovician magmatism has striking similarities with other correlatives from the Iberian, Bohemian and Armorican massifs that are discussed in this paper. This comparison reinforces the probable existence of a large-scale crustal melting process linked to a significant episode of extension on the northern Gondwana margin that probably resulted in the birth of the Rheic Ocean

Normal crossings degenerations of symplectic manifolds

We use local Hamiltonian torus actions to degenerate a symplectic manifold to a normal crossings symplectic variety in a smooth one-parameter family. This construction, motivated in part by the Gross-Siebert and B. Parker's programs, contains a multifold version of the usual (two-fold) symplectic cut construction and in particular splits a symplectic manifold into several symplectic manifolds containing normal crossings symplectic divisors with shared irreducible components in one step

Формирование зонной диаграммы фотонных и фононных кристаллов

Досліджено зонні особливості вхідних імпедансних характеристик необмежених і обмежених фотонного та фононного кристалів (Ф(н)К). Взаємним порівнянням залежностей коефіцієнта відбиття обмежених Ф(н)К і активної складової вхідного імпедансу необмежених Ф(н)К проаналізовано формування зонної діаграми обмеженими Ф(н)К. В результаті аналізу залежності параметрів заборонених зон обмежених Ф(н)К від кількості шарів проаналізовано степінь наближення параметрів зонної діаграми обмежених Ф(н)К до параметрів зонної діаграми необмежених Ф(н)К.Inroduction. Photon and phonon crystals are crystal structures, which just like the crystals, are characterized by zone spectral properties. The purpose of the article is to research the input impedance characteristics and formation features of the photon and phonon crystals’ zone diagrams. Impedance model and properties of unlimited crystal structure. The expressions for input impedance of unlimited one-dimensional crystal structure for waves of different nature are presented. The relationships of physical properties of the crystal structure and the mathematical features of the expressions are investigated. Impedance characteristics of photon and phonon unlimited crystals. The dependences of active and reactive components of photon and phonon unlimited crystal’s input impedance with layers of different thickness are shown. Input impedance characteristics of photon and phonon limited crystals. The dependences of active and reactive components of limited photon and phonon crystal’s input impedance are given. The conditions for waves resonant passing through photon and phonon crystals are obtained. Reflection coefficient characteristics of photon and phonon crystals. The formation of the limited photon and phonon crystal’s zone diagrams is analyzed by mutual comparison of limited photon and phonon crystal’s reflection characteristic and active component of unlimited photon and phonon crystal’s input impedance characteristics. The approximation degree of limited photon and phonon crystal’s zone diagram parameters to the unlimited photon and phonon crystal’s zone diagram parameters is quantitatively analyzed. Conclusions. The conditions for waves resonant passing through photon and phonon crystals is formulated and features of photon and phonon crystal’s zone diagram formation is investigated.Исследованы зонные особенности входных импедансных характеристик неограниченных и ограниченных фотонного и фононного кристаллов (Ф(н)К). Взаимным сравнением зависимостей коэффициента отражения ограниченных Ф(н)К и активной составляющей входного импеданса неограниченных Ф(н)К проанализировано формирование зонной диаграммы ограниченными Ф(н)К. В результате анализа зависимости параметров запрещенных зон ограниченных Ф(н)К от числа слоев проанализирована степень приближения параметров зонной диаграммы ограниченных Ф(н)К к параметрам зонной диаграммы неограниченных Ф(н)К

The universe formation by a space reduction cascade with random initial parameters

In this paper we discuss the creation of our universe using the idea of extra dimensions. The initial, multidimensional Lagrangian contains only metric tensor. We have found many sets of the numerical values of the Lagrangian parameters corresponding to the observed low-energy physics of our universe. Different initial parameters can lead to the same values of fundamental constants by the appropriate choice of a dimensional reduction cascade. This result diminishes the significance of the search for the 'unique' initial Lagrangian. We also have obtained a large number of low-energy vacua, which is known as a 'landscape' in the string theory.Comment: 17 pages, 1 figur