2,288 research outputs found
A theorem on lower semicontinuity of integral functionals
No full textA general lower semicontinuity theorem, in which not only mappings u(M) and P-M but also the integrands f(M) depend on M, is proved for integrands f, f(M) under certain general hypotheses. These include that f(x, u, P) is convex with respect to P and f(M) converge to f locally uniformly, but f(M)(x, u, P) are not required to be convex with respect to P and f(M)(x,.,.) do not even need to be lower semicontinuous. Some more usable criteria for lower semicontinuity of integral functionals are also given as corollaries of the main theorem.Mathematics, AppliedMathematicsSCI(E)6ARTICLE363-37412
Kaon productions off nucleons and the structure of baryon resonances
No full textThe recent investigations in the chiral quark model show that kaon productions of nucleons play an important role in understanding the structure of baryons. The evidences of a third S-11 resonance in the second resonance region and two narrow states around 2 GeV suggest a set of the molecular type baryons with the hidden strangeness. Confirming these states requires further theoretical and experimental studies of the strangeness production.Astronomy & AstrophysicsPhysics, NuclearPhysics, Particles & FieldsCPCI-S(ISTP)
Laminated Microstructure in a Variational Problem with a Non-Rank-One Connected Double Well Potential
No full textAbstractA variational problem with a non-rank-one connected double well potential is considered. It is proved that the problem has a laminated microstructure solution which is uniquely determined by the two potential wells yet certainly not characterized by the fine oscillations between them because of the lack of rank-one connection. The laminated microstructure is explicitly worked out. It is also shown that an application of a nonconforming finite element method can cause overrelaxation and fail to approximate the right microstructure
LEARNING IN AN OSCILLATORY CORTICAL MODEL
No full textWe study a model of generalized-Hebbian learning in asymmetric oscillatory neural networks modeling cortical areas such as hippocampus and olfactory cortex. The learning rule is based on the synaptic plasticity observed experimentally, in particular long-term potentiation and long-term depression of the synaptic efficacies depending on the relative timing of the pre- and postsynaptic activities during learning. The learned memory or representational states can be encoded by both the amplitude and the phase patterns of the oscillating neural populations, enabling more efficient and robust information coding than in conventional models of associative memory or input representation. Depending on the class of nonlinearity of the activation function, the model can function as an associative memory for oscillatory patterns (nonlinearity of class II) or can generalize from or interpolate between the learned states, appropriate for the function of input representation (nonlinearity of class I). In the former case, simulations of the model exhibits a first order transition between the "disordered state" and the "ordered" memory state
Iwasawa theory for modular forms at supersingular primes
No full textLet f=\sum a_nq^n be a normalised eigen-newform of weight k\ge2 and p an odd prime which does not divide the level of f. We study a reformulation of Kato's main conjecture for f over the Zp-cyclotomic extension of Q. In particular, we generalise Kobayashi's main conjecture on p-supersingular elliptic curves over Q with a_p=0, which asserts that Pollack's p-adic L-functions generate the characteristic ideals of some \pm-Selmer groups which are cotorsion over the Iwasawa algebra \Lambda=Zp[[Zp]].
We begin by studying the p-adic Hodge theory for the p-adic representation associated to f in the case when a_p=0. It allows us to give analogous definitions of Kobayashi's \pm-Coleman maps and \pm-Selmer groups. The Coleman maps are used to show that the Pontryagin duals of these new Selmer groups are torsion over \Lambda as in the elliptic curve case. As a consequence, we formulate a main conjecture stating that Pollack's p-adic L-functions generate their characteristic ideals. Similar to Kobayashi's works, we prove one inclusion of the main conjecture using an Euler system constructed by Kato.
We then prove the other inclusion of the main conjecture for CM modular forms, generalising works of Pollack and Rubin on CM elliptic curves. As a key step of the proof, we generalise the reciprocity law of Coates-Wiles and Rubin.
Next, we study Wach modules associated to positive crystalline p-adic representations in general and generalise the construction of the Coleman maps. By applying this to modular forms with much more general a_p, we define two Coleman maps and decompose the classical p-adic L functions of f into linear combinations of two power series of bounded coefficients generalising works of Pollack (in the case a_p=0) and Sprung (when f corresponds to an elliptic curve over Q with a_p\ne0). Once again, this leads to a reformulation of Kato's main conjecture involving cotorsion Selmer groups and p-adic L-functions of bounded coefficients. One inclusion of this new main conjecture is proved in the same way as the a_p=0 case.
Finally, we explain how the \pm-Coleman maps can be extended to Lubin-Tate extensions of height 1 in place of the Zp-cyclotomic extension. This generalises works of Iovita and Pollack for elliptic curves over Q
A regularized mesh transformation method for the computation of crystalline microstructures
No full textSince the finite-element approximations of microstructures are strongly mesh dependent, the use of the mesh transformation method based on the energy minimizing principle is considered a natural approach in the finite-element computation of microstructures. However, without a control on the mesh quality, the mesh can become increasingly irregular in the process of energy minimization and thus jeopardize the convergence of the algorithm. In this paper, a mesh quality control term based on the mesh regularity is introduced to regularize the mesh transformation procedure. The existence and convergence of the regularized mesh transformation method are proved. Numerical experiments show that the method does help to produce much better numerical results in the computation of microstructures. (c) 2005 Elsevier Ltd. All rights reserved.Computer Science, Interdisciplinary ApplicationsComputer Science, Software EngineeringMathematics, AppliedSCI(E)EI2ARTICLE8-9903-9144
Performance of ZP-OFDM for vehicular communication
No full textThis thesis is concerned with Evaluation of vehicular Wireless communication with the different type of channel Model, concerned with different estimation and equalisation method for vehicular communication. After a general introduction of the main concept of the Vehicular nets, the principles of wireless communication is described. Wireless Channel model is mentioned at first. Bit Error Rate as a most important metric to evaluate each type of communication channel is explained in a subchapter in second chapter. Inter symbol interference (ISI) is explained as an important phenomenon which occurs because of multipath propagation nature of wireless communication in second chapter. Doppler Effect is the next important explained phenomenon which arises from the mobility of signal scatterers. Finally, in this section, we explained the OFDM channel estimation and equalisation which is one of the main methods in Vehicular communication scenario. In Next chapter, the author introduced the different attempts to vehicular channel modelling concerned the stochastic channel model. The author mentioned the papers which concerned the Doppler Effect in channel modelling and channel simulation in vehicular environment. Afterwards, some of the vehicular channel estimations and equalisations methods are mentioned. At the fourth chapter, we made the simulation in MATLAB with the vehicular channel model, Vehicular - high antenna channel model with the most optimise Doppler frequency for the vehicular scenario which mentioned in the previous chapter. The methods that author used for this evaluation in this thesis for channel identifications and equalisations were zero forcing and overlap add methods based on ZP-OFDM scheme compared with the standard CP-OFDM. In this work, author used for first time the ZP-OFDM-OLA and ZP-OFDM-ZF channel equalizers to compare the result with the standard CP-OFDM. Finally, author compared the Symbol Error Rate (SER) per different SNR in different road environments.Diese Arbeit befasst sich mit der Evaluierung der Fahrzeug-Drahtloskommunikation mit dem verschiedenen Modelltypen, die sich mit einer unterschiedlichen Schätz- und Entzerrungsmethode fu?r die Fahrzeugkommunikation beschäftigt. Nach einer allgemeinen Einfu?hrung des Hauptkonzepts der Vehicle Netze werden die Prinzipien der drahtlosen Kommunikation beschrieben. Drahtloses Kanalmodell wird zuerst erwähnt. Die Bitfehlerrate als wichtigste Metrik zur Bewertung jedes Kommunikationstyps wird in einem Unterkapitel im zweiten Kapitel erläutert. Inter-Symbol-Interferenz (ISI) wird als ein wichtiges Phänomen erklärt, das aufgrund der Mehrwegeausbreitung der drahtlosen Kommunikation im zweiten Kapitel auftritt. Der Dopplereffekt ist das nächste wichtige erklärte Phänomen, das aus der Beweglichkeit von Signalstreuern entsteht. Schließlich, in diesem Abschnitt, erklärten wir die OFDM-Kanalschätzung und Entzerrung, die eine der Hauptmethoden im Vehicle Communication-Szenario ist. Im nächsten Kapitel fu?hrte der Autor die verschiedenen Versuche der Fahrzeugkanalmodellierung ein, die das stochastische Kanalmodell betreffen. Der Autor erwähnte die Papiere, die den Dopplereffekt in der Kanalmodellierung und Kanalsimulation im Fahrzeugumfeld betreffen. Danach werden einige der Fahrzeugkanalschätzungen und -gleichungen genannt. Im vierten Kapitel haben wir die Simulation in MATLAB mit dem Fahrzeugkanalmodell Vehicle - high Antennenkanalmodell mit der optimalen Dopplerfrequenz fu?r das Fahrzeugszenario, das im vorigen Kapitel erwähnt wurde, durchgefu?hrt. Die Methoden, die der Autor fu?r diese Evaluierung in dieser Arbeit fu?r Kanalidentifikationen und -gleichungen verwendet hat, waren null-erzwungene und u?berlappende Add-Methoden basierend auf dem ZP-OFDM-Schema im Vergleich zum Standard-CP-OFDM. In dieser Arbeit verwendet der Autor zum ersten Mal die ZP-OFDM-OLA- und ZP-OFDM-ZF-Kanalentzerrer, um das Ergebnis mit dem Standard-CP-OFDM zu vergleichen. Schließlich verglich der Autor die Symbol Error Rate (SER) pro verschiedenen SNR in verschiedenen Straßenumgebungen. Schlagwörter:Masterarbeit Wien, FH Technikum Wien 201
Strict ergodicity of affine p-adic dynamical systems on Zp
No full textAbstractLet p⩾2 be a prime number and let Zp be the ring of all p-adic integers. For all α,β,z∈Zp, define Tα,β(z)=αz+β. It is shown that the dynamical system (Zp,Tα,β) is minimal if and only if α∈1+prpZp and β is a unit, here rp=1 (respectively rp=2) if p⩾3 (respectively if p=2), and that when it is minimal, it is strictly ergodic and topologically conjugate to (Zp,T1,1) with an analytic and isometric conjugacy. More importantly, when the system is not minimal, we find all its strictly ergodic components. As application, monomial systems Sn,ρ(z)=ρzn on the group 1+pZp are also discussed
Effects of the quantity sigma(TS) on the spin structure functions of nucleons in the resonance region
No full textIn this paper, we investigate the effects of the quantity sigma(TS) on the spin structure functions of nucleons in the resonance region. The Schwinger sum rule for the spin structure function g(2)(x,Q(2)) at the real photon limit is derived for the nucleon treated as a composite system, and it provides a crucial constraint on the longitudinal transition operator which has not been treated consistently in the literature. The longitudinal amplitude S-1/2 is evaluated in the quark model with the transition operator that generates the Schwinger sum rule. The numerical results of the quantity sigma(TS) are presented for both spin structure functions g(1)(x,Q(2)) and g(2)(x,Q(2)), in the resonance region. Our results show that this quantity plays an important role in the low Q(2) region, which can be tested in future experiments at CEBAF.Astronomy & AstrophysicsPhysics, Particles & FieldsSCI(E)30ARTICLE74301-43115
Performance analysis of the cooperative ZP-OFDM: Diversity, capacity and complexity
No full textIn this paper, we investigate the diversity, capacity and complexity issues of cooperative Zero-Padding (ZP)-Orthogonal FrequencyDivisionMultiplexing (OFDM) communication. We consider cooperative ZP-OFDM communication over a multipath Rayleigh channel and with multiple Carrier Frequency Offsets (CFOs) existing at different relays. We use a cooperative tall Toeplitz scheme to achieve full cooperative and multipath diversity, while simultaneously combat the CFOs. Importantly, this full diversity scheme only requires Linear Equalizers (LEs), such as Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) equalizers, an issue which reduces the system complexity when compared to a Maximum-Likelihood Equalizer (MLE) or other near-MLEs. Theoretical analysis of the proposed cooperative tall Toeplitz scheme is provided on the basis of the analytical upper bound of the channel orthogonality deficiency derived in this paper. Utilizing only low-complexity linear equalizers, theoretical analysis and simulation results show that the proposed Toeplitz scheme achieves the full cooperative, multipath and outage diversity.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
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