Fractional-order harmonics in the trajectory control of redundant manipulators

Redundant manipulators are superior to classical arms because they allow the trajectory optimization, the obstacle avoidance, and the resolution of singularities. For this type of manipulators, the kinematic control algorithms adopt generalized inverse matrices that may lead to unpredictable responses. Motivated by these problems this paper studies the complexity revealed by the trajectory planning scheme when controlling redundant manipulators. The result reveals a chaotic phenomenon and the existence of fractional order sub-harmonics in the robot signals.N/

Fractional dynamics in the trajectory control of redundant manipulators

Under the pseudoinverse control, robots with kinematical redundancy exhibit an undesirable chaotic joint motion which leads to an erratic behavior. This paper studies the complexity of fractional dynamics of the chaotic response. Fourier and wavelet analysis provides a deeper insight, helpful to know better the lack of repeatability problem of redundant manipulators. This perspective for the study of the chaotic phenomena will permit the development of superior trajectory control algorithms

2-Methyl-5-(4-tol­yl)-7-(trifluoro­meth­yl)pyrazolo[1,5-a]pyrimidine

In the title compound, C15H12F3N3, the pyrazolo[1,5-a]pyrimidine system ring is essentially planar with a maximum deviation from the mean plane of 0.014 (1) Å. The 4-tolyl group makes a dihedral angle of 14.1 (1)° with the pyrazolo[1,5-a]pyrimidine ring system. The crystal packing is stabilized mainly by van der Waals forces

A distributed computation of Interpro Pfam, PROSITE and ProDom for protein annotation

Interpro is a widely used tool for protein annotation in genome sequencing projects, demanding a large amount of computation and representing a huge time-consuming step. We present a strategy to execute programs using databases Pfam, PROSITE and ProDom of Interpro in a distributed environment using a Java-based messaging system. We developed a two-layer scheduling architecture of the distributed infrastructure. Then, we made experiments and analyzed the results. Our distributed system gave much better results than Interpro Pfam, PROSITE and ProDom running in a centralized platform. This approach seems to be appropriate and promising for highly demanding computational tools used for biological applications

Magneto-structural versatility of copper(ii)-3-phenylpropionate coordination polymers with N-donor coligands

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)A novel series of copper(II) coordination polymers [Cu-2(O2CC8H9)(4)(pyz)](n) (1), [Cu-2(O2CC8H9)(4)(dps)](n) (2), {[Cu(O2CC8H9)(2)(dps)(H2O)]center dot H2O}(n) (3), {[NaCu(O2CC8H9)(2)(bpm)(NO3)]center dot H2O}(n) (4), and [Cu-4(O2CC8H9)(6)-(OH)(2)(bpp)(2)](n) (5) [O2CC8H9- = 3-phenylpropionate anion, pyz = pyrazine, dps = di(4-pyridyl)sulfide, bpm = 2,2'-bipyrimidine, and bpp = 1,3-bis(4-pyridyl)propane] have been synthesized and magneto-structurally investigated. Compounds 1 and 2 belong to a large group of copper(II) carboxylates where bis-monodentate pyz (1) and dps (2) ligands connect the paddle-wheel [Cu-2(II)(mu-O2CC8H9)(4)] units leading to alternating copper(II) chains. The structure of 3 consists of uniform chains of trans-[Cu-II(O2CC8H9)(2)] units linked by the bis-monodentate dps ligand. Compound 4 consists of heterobimetallic chains where [(Na2Cu2II)-Cu-I(mu-O2CC8H9)(4)(NO3)(2)] units are doubly bridged by bis-bidentate bpm ligands. Compound 5 is also a chain compound whose structure is made up by tetranuclear [Cu-4(II)(mu(3)-OH)(2)(mu-O2CC8H9)(4)(O2CC8H9)(2)] units which are doubly bridged by bis-monodentate bpp ligands. The magnetic properties were investigated in the temperature range 1.8-300 K. Strong antiferromagnetic interactions across the quadruple syn-syn carboxylate are observed in 1 and 2 [J = -378 (1) and -348 cm(-1) (2)] whereas a weak ferromagnetic coupling through the double out-of-plane oxo(carboxylate) bridge occurs in 4 [J = +2.66 cm(-1)], the spin Hamiltonian being defined as H = -JS(1).S-2 with S-1 = S-2 = S-Cu = 1/2. A quasi Curie law is observed for 3 (theta = -0.36 cm(-1)), the bis-monodentate dps ligand being a very poor mediator of magnetic interactions. The analysis of the magnetic properties of 5 is quite complex because of the presence of two crystallographically independent tetracopper(II) units with single-mu-hydroxo, di-mu-hydroxo, mu(3)-hydroxo and single-mu-hydroxo plus double syn, syn carboxylate bridges in each one. The nature and values of the magnetic couplings for 5 obtained by fitting (intermediate, strong and weak antiferromagnetic interactions for the three former exchange pathways respectively, and intermediate ferromagnetic interactions for the latter one) were substantiated by DFT type calculations.A novel series of copper(II) coordination polymers [Cu2(O2CC8H9)4(pyz)]n (1), [Cu2(O2CC8H9)4(dps)]n (2), {[Cu(O2CC8H9)2(dps)(H2O)]·H2O}n (3), {[NaCu(O2CC8H9)2(bpm)(NO3)]·H2O}n (4), and [Cu4(O2CC8H9)6(OH)2(bpp)2]n (5) [O2CC8H9− = 3-phenylpropionate anion,451172189CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE MINAS GERAIS - FAPEMIGCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)sem informaçãosem informaçãosem informaçãoThe authors thank the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico (CNPq), the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), FINEP (ref. 134/08

Fractional order dynamical systems and its applications

This article illustrates several applications of fractional calculus (FC) in science and engineering. It has been recognized the advantageous use of this mathematical tool in the modeling and control of many dynamical systems. In this perspective, this paper investigates the use of FC in the following fields: Controller tuning; Electrical systems; Traffic systems; Digital circuit synthesis; Evolutionary computing; Redundant robots; Legged robots; Robotic manipulators; Nonlinear friction; Financial modeling.N/