COMPUTER SYNTHESIS AND OPTIMIZATION OF JUMPING MOTIONS VIA NONSTATIONARY CONSTRAINTS

Introduction: This report considers the results of the authors’ research on the goal-oriented computer synthesis of human motions in support and non-support phases. The main attention is paid to the synthesis of the pushing phases. In particular, an analysis is made of the results of a sequential optimization of running long jumps and acrobatic jumps. The computer modeling of complex coordination motions is based on the development of an adequate anthropomorphic model. Methods and Results: Most effective in the developed modeling system proved to be the employment of differentiated non-stationary holonomic and nonholonomic constraints equations in order to model goal-oriented motions [1]. For descriptions of additional non-stationary items in constraints equations we used parametrically controlled smooth approximation functions which allowed us to synthesize the desired motion trajectories, ground reaction force and kinetic moment increment. Due to the non-stationary nature of constraints equations, any experimental data on kinematics and/or the dynamics of real motion can fulfill their function. For the analysis of modeling results we consider estimates of interelement control motions distribution in the support phase of jumping motion. A number of anthropomorphic model (AM) elements can change with respect to the level of AM adequacy to real human motion. For example, we used a 15-element AM for modeling the support and flying phases of the running long jump. Analysis of synthesized inter-element control moments values showed that the most significant influence on the value of the ground reaction and, therefore, on the pushingoff velocity was the motion of the swinging nonsupport leg. Variation of the parameters values of ground reaction and the resulting value of the kinetic moment allowed us to synthesize the AM motion in the support phase so that it would ensure the desired trajectory of the AM motion in the flying phase of acrobatic motions. Conclusions: Research showed the necessity of employment of non-stationary constraint equations in the synthesis of complex coordination human motions. Such an approach to motion control synthesis minimizes the number of parameters to be varied and gives a relatively stable solution with respect to small variations of AM structure. REFERENCES: 1. Zinkovsky, A.V., Sholuha, V.A., Ivanov, A.A. (1997). Mathematical Modeling and Computer Simulation of Biomechanical Systems, WSP, Singapore, 216

PRINCIPLES OF ADEQUACY CRITERIA FORMULATION IN HUMAN MOTION ANALYSIS

Introduction. Number of parameters of an anthropomorphic model (AM), which simulates real human motion, can achieve the value of one hundred and even more than that. This makes obvious the necessity of adequacy criteria formulation. Optimal value of such criteria should indicate structural and parametric adjustment of AM to certain real human motion. Modelling of human motion with employment of mechanical-mathematical apparatus of system of body motion equations implies a significant number of problem parameters [1] required for description of the structure, and components and kinematics of motion as well. Choice of these parameters values seriously depends on what experimental data is available. METHODS AND RESULTS: The base of computer model consists in a system of differential-algebraic equations of motion of a ramified kinematics chain with nonstationary constraints. In particular, as constraint equations there can serve generalized coordinates behaviour functions, obtained through video-registration data processing. Such approach allows to determine main dynamic values, including generalized forces. However, measurement errors lead to significant errors in assessed values of inter-element forces and moments and especially values of external with respect to AM ground reaction and total moment of external forces in support phase of motion. Variation of AM elements parameters, positions of joints, parameters of trajectories smoothing allows to obtain an averaged assessment of external forces values. In the report there is suggested a new approach to structural an parametrical adjustment of AM. Presence of non-stationary constraint equations allows to use some of experimental data for such constraints. For example, ground reaction force and/or external moment can be available or equal to zero during the flight phase. One of investigation result is that there have been analyzed grand circles on the horizontal bar with a following jump off the bar and four backward somersaults performed in a grouped position. The number of AM elements is widely varied. There has been investigated influence of possible errors in determination of visco-elastic properties of the bar on the analysis results for different processing procedures. CONCLUSION: The suggested approach to iterational parametric adjustment of AM on the basis of employing of constraint equations allows for complete matching of model motion characteristics with most important experimental data. Less important data are estimated in average, which corresponds to traditional structural- parametric adjustment of AM. REFERENCES: 1. Zinkovsky A.V., Sholuha V.A., Ivanov A.A. Mathematical Modelling and Computer Simulation of Biomechanical Systems, WSP, Singapore, 1997. 216p

Phase Composition and Defect Substructure of Strengthening Layer Surfaced on Low Alloyed Steel

The microstructure and microhardness distribution in surface of low carbon Hardox 450 steel coated with alloyed powder wires of different chemical compositions are studied. It is shown that the microhardness of 6-8 mm thickness surfaced layer exceeds that of base metal by more than 2 times. The increased mechanical properties of surfaced layer are caused by the submicro and nanoscale dispersed martensite, containing the niobium carbides Nb2C, NbC and iron borides Fe2B. In the bulk plates a dislocation substructure of the net-like type with scalar islocation density of 10^11 cm^-2 is observed. The layer surfaced with the wire containing B possesses the highest hardness. The possible mechanisms of niobium and boron carbides formation in surfacing are discusse

Primary Sequences of Protein-Like Copolymers: Levy Flight Type Long Range Correlations

We consider the statistical properties of primary sequences of two-letter HP copolymers (H for hydrophobic and P for polar) designed to have water soluble globular conformations with H monomers shielded from water inside the shell of P monomers. We show, both by computer simulations and by exact analytical calculation, that for large globules and flexible polymers such sequences exhibit long-range correlations which can be described by Levy-flight statistics.Comment: 4 pages, including 2 figures; several references added, some formulations improve

Incorporation of CdS nonoparticles from colloidal solution into optically clear ureasilicate matrix with preservation of quantum size effect

Nanocomposite materials based on an organic-inorganic ureasilicate matrix with embedded CdS nanoparticles were produced and characterized by optical (UV/Vis), FTIR, secondary ion mass spectroscopy, inductively-coupled plasma optical emission and steady-state photoluminescence measurements. The ureasilicate precursor was obtained by the reaction between silicon alkoxyde modified by isocyanate groups and polyethylene glycol oligomers with amine terminal groups. The final nanocomposites were prepared by introducing a colloidal solution of CdS nanoparticles with various sizes into the ureasilicate precursor followed by gelation of the mixture in the presence of ammonia/water vapours. The reliable preservation of the quantum-size effect of nanoparticles after their incorporation into the ureasilicate matrix was observed in all samples. The obtained materials were optically transparent at visible range, exhibiting high flexibility and long-term stability.This work has been supported by the Fundação para a Ciência e a Tecnologia (FCT) V.Boev and A.Soloviev thank the FCT for research grants SFRH/BD/3188/2000 and SFRH/BPD/18098/2004 respectively

Quantum-to-Classical Correspondence and Hubbard-Stratonovich Dynamical Systems, a Lie-Algebraic Approach

We propose a Lie-algebraic duality approach to analyze non-equilibrium evolution of closed dynamical systems and thermodynamics of interacting quantum lattice models (formulated in terms of Hubbard-Stratonovich dynamical systems). The first part of the paper utilizes a geometric Hilbert-space-invariant formulation of unitary time-evolution, where a quantum Hamiltonian is viewed as a trajectory in an abstract Lie algebra, while the sought-after evolution operator is a trajectory in a dynamic group, generated by the algebra via exponentiation. The evolution operator is uniquely determined by the time-dependent dual generators that satisfy a system of differential equations, dubbed here dual Schrodinger-Bloch equations, which represent a viable alternative to the conventional Schrodinger formulation. These dual Schrodinger-Bloch equations are derived and analyzed on a number of specific examples. It is shown that deterministic dynamics of a closed classical dynamical system occurs as action of a symmetry group on a classical manifold and is driven by the same dual generators as in the corresponding quantum problem. This represents quantum-to-classical correspondence. In the second part of the paper, we further extend the Lie algebraic approach to a wide class of interacting many-particle lattice models. A generalized Hubbard-Stratonovich transform is proposed and it is used to show that the thermodynamic partition function of a generic many-body quantum lattice model can be expressed in terms of traces of single-particle evolution operators governed by the dynamic Hubbard-Stratonovich fields. Finally, we derive Hubbard-Stratonovich dynamical systems for the Bose-Hubbard model and a quantum spin model and use the Lie-algebraic approach to obtain new non-perturbative dual descriptions of these theories.Comment: 25 pages, 1 figure; v2: citations adde

Robust cryogenic matched low-pass coaxial filters for quantum computing applications

Electromagnetic noise is one of the key external factors decreasing superconducting qubits coherence. Matched coaxial filters can prevent microwave and IR photons negative influence on superconducting quantum circuits. Here, we report on design and fabrication route of matched low-pass coaxial filters for noise-sensitive measurements at milliKelvin temperatures. A robust transmission coefficient with designed linear absorption (-1dB/GHz) and ultralow reflection losses less than -20 dB up to 20 GHz is achieved. We present a mathematical model for evaluating and predicting filters transmission parameters depending on their dimensions. It is experimentally approved on two filters prototypes different lengths with compound of Cu powder and Stycast commercial resin demonstrating excellent matching. The presented design and assembly route are universal for various compounds and provide high repeatability of geometrical and microwave characteristics. Finally, we demonstrate three filters with almost equal reflection and transmission characteristics in the range from 0 to 20 GHz, which is quite useful to control multiple channel superconducting quantum circuits.Comment: 5 pages, 4 figure

Mineralogy of the inclusions and age of zircon from granite basement of Verkhnerechensk area (Yamal peninsula)

The study of minerals-prisoners in accessory zircons is gradually evolving into an important geological-petrological task. Such a study can show not only the earliest mineral rock association, but also evaluate the “sealed” mineral paragenesis of zircon, which in turn indicates whether the accessory zircon is native to the host rock or redeposited (alien). In the present work, the mineralogy of zircon from granitoids of the crystalline basement of the Verkhnerechensk oil-exploration area (the southern part of the Yamal Peninsula, Western Siberia) has been studied. Granitoids are represented by homogeneous light gray fine-grained variety of biotite-quartz-feldspar composition and refer to monzoleucogranite, which formed over the sedimentary substrate, most likely under conditions of late orogenic surrounding. The time of magmatic intrusion and crystallization of granites according to the data of U-Pb dating of zircon (measurements carried out on the ion microprobe SHRIMP-II) is estimated as Late Permian (254.0 ± 3.0 (MSWD = 1.6) Ma). It is established that inclusions in zircon are represented by various minerals - fluorapatite, titanite, monazite-(Ce), albite, quartz, chamosite and calcite. The last two minerals, apparently, were not formed together with zircon, but are later secondary minerals formed as a result of the propylization of the rock. The time of secondary changes in the granitoid supposedly occurred in the Late Triassic, as one of the zircons gave a U-Pb dating of 204.7 ± 2.6 Ma. In general, accessory zircons and mineral inclusions contained in them belong to the “granite” association, and, apparently, are native to the enclosing monzoleucogranite

Gradient non-woven fabrics with a modified surface nanolayer for water filtration in construction industry

ABSTRACT: Introduction. The aim of the work is to determine the influence of the structure of the filter materials formed as a result of modification of the surface layer on their water permeability and the size of trapped solid particles. Materials and methods. The non-woven fabrics from a mixture of polyethylene-terephthalate (PET) (70 wt.%) and bicomponent fibers (BCF) of the coreshell structure were used as objects of the study. The non-woven fabrics were obtained by mechanically forming the canvas with its subsequent hardening by needle punching. The resulting materials were modified by heat treatment. The water transfer in the modified materials was determined by the permeability coefficient. The filtration efficiency was determined by the number of trapped particles of a certain size. Results and discussion. The needle-punched non-woven fabrics without additional heat treatment are not suitable for water filtration. The proposed method of thermal and deformation-thermal modification provides the production of gradient materials with a controlled thickness of the nanoscale surface layer. Although a decrease in water permeability is observed, the modified material traps solid particles with a smaller (compared to unmodified ~ 20 µm) equivalent diameter of 2–4 µm, which is sufficient to prepare water for use in steam generators and in the production of building materials. Conclusion. The optimal parameters of deformation-heat treatment for obtaining the high-effective filtration non-woven materials were established: the temperature – 180оC, the processing speed – 3.5 m/min

Crystal Structure of the Monomeric Extracellular Domain of α9 Nicotinic Receptor Subunit in Complex With α-Conotoxin RgIA: Molecular Dynamics Insights Into RgIA Binding to α9α10 Nicotinic Receptors

The α9 subunit of nicotinic acetylcholine receptors (nAChRs) exists mainly in heteropentameric assemblies with α10. Accumulating data indicate the presence of three different binding sites in α9α10 nAChRs: the α9(+)/α9(−), the α9(+)/α10(−), and the α10(+)/α9(−). The major role of the principal (+) side of the extracellular domain (ECD) of α9 subunit in binding of the antagonists methyllylcaconitine and α-bungarotoxin was shown previously by the crystal structures of the monomeric α9-ECD with these molecules. Here we present the 2.26-Å resolution crystal structure of α9-ECD in complex with α-conotoxin (α-Ctx) RgIA, a potential drug for chronic pain, the first structure reported for a complex between an nAChR domain and an α-Ctx. Superposition of this structure with those of other α-Ctxs bound to the homologous pentameric acetylcholine binding proteins revealed significant similarities in the orientation of bound conotoxins, despite the monomeric state of the α9-ECD. In addition, ligand-binding studies calculated a binding affinity of RgIA to the α9-ECD at the low micromolar range. Given the high identity between α9 and α10 ECDs, particularly at their (+) sides, the presented structure was used as template for molecular dynamics simulations of the ECDs of the human α9α10 nAChR in pentameric assemblies. Our results support a favorable binding of RgIA at α9(+)/α9(−) or α10(+)/α9(−) rather than the α9(+)/α10(−) interface, in accordance with previous mutational and functional data