The output torque estimation of MCMG for agile satellites

Studied in this paper are the attitude control law design and the output torque estimation problem of micro control moment gyros （MCMGs） for the agile satellites executing rapid attitude maneuver mission. An algorithm is proposed for estimating the output torques and the gimbal angular rates of MCMGs, which can help engineers to choose reasonable size for actuators so that the cost of satellite can be decreased. According to some special maneuver missions, a numerical example of attitude control system for a small satellite with MCMGs in pyramid configuration is studied, and the simulation results validate the proposed estimation algorithm.     

Construction of the Control Realizing the Rotation of a Timoshenko Beam

We consider the linear model of a slowly rotating Timoshenko beam in a horizontal plane whose moment is controlled by the angular acceleration of the disk of the driving motor into which the beam is clamped. This work complements our previous results on the controllability of the beam from a position of rest into another position of rest; we give a method of construction of a piecewise constant control solving the problem.     

Neutron scattering of fragile antiferromagnetic phases in heavy fermion compounds

Results of neutron scattering and specific heat measurements are reported for two kinds of weak antiferromagnetic compounds corresponding to (i) the situation at the quantum critical point and (ii) the double magnetic transition observed in CeRu₂Ge₂.     

Chemical Shift and Its Uses as an Electronic Parameter in Structure-Activity Correlations

Apparent correlations are found between the N-H chemical shifts of congeneric series of compounds and the dipole moments of the molecules, such as lactams and thiolactams, cyclic ureas and thioureas. When there is a high degree of correlation, either the N-H chemical shift or the dipole moment of the molecule can be used as an electronic parameter in correlating the biological activity with the chemical structure. In a series of substituted salicylaldehydes the Hammett σ constant gives better correlation with the biological activity than the O-H chemical shift. This is probably due to the anisotropic effect of the substituent besides the electronic effect. Other factors affecting the N-H chemical shift, e.g. intramolecular hydrogen-bonding of nitrosoureas and the deshielding effect of a benzene ring, in o-phenyleneureas are also presented. In spite of the limitations, the chemical shifts of many compounds can be obtained very easily, therefore, their uses in structure-activity correlations deserve further investigation.     

Applications of the molecular orbital graph theory (XI)

The tree graph method of evaluating the local molecular moment is proposed. By applying this method and the molecular moment formula of π-electron energy in the molecular orbital graph theory, a topological method of using the molecular moment to judge the relatively reactive point of even AH is achieved.     

LCAO-MO Calculation of Dipole Transition Moment of Some First-Row Transition Metal Tetroxy Anions

Abstract

Recently very encouraging results of semiempirical parameteric calculation of dipole transition moments of the lowest energy t₁ ? 2e (¹A₁ - ¹T₂) transition of permanganate and chromate ions have been reported. In the case of vanadate ion, which is isoelectronic with the permanganate and chromate ion, no such study of spectral intensities appears to have been reported so far. A parameteric calculation in terms of a single parameter β, the ligand mixing coefficient using Richardson's orbitals⁴ and both dipole velocity and dipole length operators have been reported in the present paper.     

Convergence on layer-adapted meshes and anisotropic interpolation error estimates of non-standard higher order finite elements

For a general class of finite element spaces based on local polynomial spaces E with Pp⊂E⊂Qp we construct a vertex-edge-cell and point-value oriented interpolation operators that fulfil anisotropic interpolation error estimates.Using these estimates we prove ε-uniform convergence of order p for the Galerkin FEM and the LPSFEM for a singularly perturbed convection-diffusion problem with characteristic boundary layers.     

Analytical and numerical results for the Swift-Hohenberg equation

The problem of the Swift-Hohenberg equation is considered in this paper. Using homotopy analysis method (HAM) the series solution is developed and its convergence is discussed and documented here for the first time. In particular, we focus on the roles of the eigenvalue parameter α and the length parameter l on the large time behaviour of the solution. For a given time t, we obtain analytical expressions for eigenvalue parameter α and length l which show how different values of these parameters may lead to qualitatively different large time profiles. Also, the results are presented graphically. The results obtained reveal many interesting behaviors that warrant further study of the equations related to non-Newtonian fluid phenomena, especially the shear-thinning phenomena. Shear thinning reduces the wall shear stress.     

Dynamically Equilibrium Shape of Intrusive Vortex Formations in the Ocean

The problem of finding the dynamically equilibrium shape of a rotating mass of liquid with homogeneous density (lens) submerged in a stratified ocean at rest on the rotating Earth is formulated. An equation for the shape of the interface between water masses is derived. An exact solution of the problem for an anticyclonically rotating lens in a linearly stratified ocean in the neighborhood of the lens depth shows that the dynamically equilibrium shape of the interface is a triaxial ellipsoid inclined with respect to the horizon and similar to an ellipsoid of revolution for real parameters of the phenomenon. The limiting values of the latitudes at which these formations can exist are determined. Degeneration of the shape with decrease in the intrinsic lens angular rate is investigated.