An Implementable and Stabilizing Model Predictive Control Strategy for Inverted Pendulum-Like Behaved Systems

In control theory, the inverted pendulum is a class of dynamic systems widely used as a benchmarking for evaluating several control strategies. Such a system is characterized by an underactuated behavior. It is also nonlinear and presents open-loop unstable and integrating modes. These dynamic features make the control more difficult, mainly when the controller synthesis seeks to include constraints and the guarantee of stability of the closed-loop system. This chapter presents a stabilizing model predictive control (MPC) strategy for inverted pendulum-like behaved systems. It has an offset-free control law based on an only optimization problem (one-layer control formulation), and the Lyapunov stability of the closed-loop system is achieved by adopting an infinite prediction horizon. The controller feasibility is also assured by imposing a suitable set of slacked terminal constraints associated with the unstable and integrating states of the system. The effectiveness of the implementable and stabilizing MPC controller is experimentally demonstrated in a commercial-didactic rotary inverted pendulum prototype, considering both cases of stabilization of the pendulum in the upright position and the output tracking of the rotary arm angle

Symmetry restoration of the soft pion corrections for the light sea quark distributions in the small xx region

The soft pion correction at high energy may play a crucial role in non-perturbative parts of sea quark distributions. In this paper, we show that, while the soft pion correction for the strange sea qaurk distribution is suppressed in the large and the medium $x$ region compared with that for the up and the down sea quark one, it can become large and SU(3) flavor symmetric in the very small $x$ region. This gives us a good reason for the symmetry restoration of light sea quark distributions required by the mean charge sum rule for the light sea quarks. Then, by estimating this sum rule with the help of the results obtained by the soft pion correction, it is argued that there is a large symmetry restoration of the strange sea quark in the region from $x=10^{-2}$ to $10^{-6}$ at $Q^2\sim 1$ GeV.Comment: 22 pages including 4 eps figures, ReVTeX, to appear in Phys. Rev.

Limits on excited tau leptons masses from leptonic tau decays

We study the effects induced by excited leptons on the leptonic tau decay at one loop level. Using a general effective lagrangian approach to describe the couplings of the excited leptons, we compute their contributions to the leptonic decays and use the current experimental values of the branching ratios to put limits on the mass of excited states and the substructure scale.Comment: 10 pages, 6 figures, to be published in Phys. Rev.

Nonexotic Neutral Gauge Bosons

We study theoretical and experimental constraints on electroweak theories including a new color-singlet and electrically-neutral gauge boson. We first note that the electric charges of the observed fermions imply that any such Z' boson may be described by a gauge theory in which the Abelian gauge groups are the usual hypercharge along with another U(1) component in a kinetic-diagonal basis. Assuming that the observed quarks and leptons have generation-independent U(1) charges, and that no new fermions couple to the standard model gauge bosons, we find that their U(1) charges form a two-parameter family consistent with anomaly cancellation and viable fermion masses, provided there are at least three right-handed neutrinos. We then derive bounds on the Z' mass and couplings imposed by direct production and Z-pole measurements. For generic charge assignments and a gauge coupling of electromagnetic strength, the strongest lower bound on the Z' mass comes from Z-pole measurements, and is of order 1 TeV. If the new U(1) charges are proportional to B-L, however, there is no tree-level mixing between the Z and Z', and the best bounds come from the absence of direct production at LEPII and the Tevatron. If the U(1) gauge coupling is one or two orders of magnitude below the electromagnetic one, these bounds are satisfied for most values of the Z' mass.Comment: 26 pages, 2 figures. A comparison with the LEP bounds on sneutrino resonances is include

Superposition effect and clan structure in forward-backward multiplicity correlations

The main purpose of this paper is to discuss the link between forward-backward multiplicity correlations properties and the shape of the corresponding final charged particle multiplicity distribution in various classes of events in different collisions. It is shown that the same mechanism which explains the shoulder effect and the H_n vs. n oscillations in charged particle multiplicity distributions, i.e., the weighted superposition of different classes of events with negative binomial properties, reproduces within experimental errors also the forward-backward multiplicity correlation strength in e+e- annihilation at LEP energy and allows interesting predictions for pp collisions in the TeV energy region, to be tested at LHC, for instance with the ALICE detector. We limit ourselves at present to study substructures properties in hadron-hadron collisions and e+e- annihilation; they are examined as ancillary examples in the conviction that their understanding might be relevant also in other more complex cases.Comment: 16 page

Pair Production of the Lightest Chargino via Gluon-Gluon Collisions

The production of the lightest chargino pair from gluon-gluon fusion is studied in the minimal supersymmetric model(MSSM) at proton-proton colliders. We find that with the chosen parameters, the production rate of the subprocess can be over 2.7 femto barn when the chargino is higgsino-like, and the corresponding total cross section in proton-proton collider can reach 56 femto barn at the LHC in the CP-conserving MSSM. It shows that this loop mediated subprocess can be competitive with the standard Drell-Yan subprocess in proton-proton colliders, especially at the LHC. Furthermore, our calculation shows it would be possible to extract information about some CP-violating phase parameters, if we collected enough chargino pair events.Comment: 39 pages, LaTex, 8 figure

Pair production of neutralinos via gluon-gluon collisions

The production of a neutralino pair via gluon-gluon fusion is studied in the minimal supersymmetric model(MSSM) at proton-proton colliders. The numerical analysis of their production rates are carried out in the mSUGRA scenario. The results show that this cross section may reach about 80 femto barn for $\tilde{\chi}^{0}_{1}\tilde{\chi}^{0}_{2}$ pair production and 23 femto barn for $\tilde{\chi}^{0}_{2}\tilde{\chi}^{0}_{2}$ pair production with suitable input parameters at the future LHC collider. It shows that this loop mediated process can be competitive with the quark-antiquark annihilation process at the LHC.Comment: LaTex file, l4 pages, 5 EPS figure

Searching for a light Fermiophobic Higgs Boson at the Tevatron

We propose new production mechanisms for light fermiophobic Higgs bosons ($h_f$) with suppressed couplings to vector bosons ($V$) at the Fermilab Tevatron. These mechanisms (e.g. $qq'\to H^\pm h_f$) are complementary to the conventional process $qq'\to Vh_f$, which suffers from a strong suppression of $1/\tan^2\beta$ in realistic models with a $h_f$. The new mechanisms extend the coverage at the Tevatron Run II to the larger $\tan\beta$ region, and offer the possibility of observing new event topologies with up to 4 photons.Comment: 15 pages, including 5 eps-figure

Soil organisms in organic and conventional cropping systems.

Apesar do crescente interesse pela agricultura orgânica, são poucas as informações de pesquisa disponíveis sobre o assunto. Assim, num Argissolo Vermelho-Amarelo distrófico foram comparados os efeitos de sistemas de cultivo orgânico e convencional, para as culturas do tomate (Lycopersicum esculentum) e do milho (Zea mays), sobre a comunidade de organismos do solo e suas atividades. As populações de fungos,bactérias e actinomicetos, determinadas pela contagem de colônias em meio de cultura, foram semelhantes para os dois sistemas de produção. A atividade microbiana, avaliada pela evolução de CO2, manteve-se superior no sistema orgânico, sendo que em determinadas avaliações foi o dobro da evolução verificada no sistema convencional. O número de espécimes de minhoca foi praticamente dez vezes maior no sistema orgânico. Não foi observada diferença na taxa de decomposição de matéria orgânica entre os dois sistemas. De modo geral, o número de indivíduos de microartrópodos foi superior no sistema orgânico do que no sistema convencional, refletindo no maior índice de diversidade de Shannon. As maiores populações de insetos foram as da ordem Collembola, enquanto para os ácaros a maior população foi a da superfamília Oribatuloidea. Indivíduos dos grupos Aranae, Chilopoda, Dyplopoda, Pauropoda, Protura e Symphyla foram ocasionalmente coletados e de forma similar entre os sistemas

Planck scale effects in neutrino physics

We study the phenomenology and cosmology of the Majoron (flavon) models of three active and one inert neutrino paying special attention to the possible (almost) conserved generalization of the Zeldovich-Konopinski-Mahmoud lepton charge. Using Planck scale physics effects which provide the breaking of the lepton charge, we show how in this picture one can incorporate the solutions to some of the central issues in neutrino physics such as the solar and atmospheric neutrino puzzles, dark matter and a 17 keV neutrino. These gravitational effects induce tiny Majorana mass terms for neutrinos and considerable masses for flavons. The cosmological demand for the sufficiently fast decay of flavons implies a lower limit on the electron neutrino mass in the range of 0.1-1 eV.Comment: 24 pages, 1 figure (not included but available upon request), LaTex, IC/92/196, SISSA-140/92/EP, LMU-09/9