Length-weight relationships of the ichthyofauna associated with the Brazilian sardine, Sardinella brasiliensis, on the Southeastern Brazilian Bight (22°S-29°S) between 2008 and 2010

In this study, estimates of length-weight relationships are presented for twenty-four species caught in association with the Brazilian sardine, Sardinella brasiliensis, during four acoustics surveys carried out under the Program ECOSAR (Prospecting and evaluation of biomass of the stock of Brazilian sardine on the southeast coast by acoustic methods), which was to evaluate the biomass of species that were caught. The model parameters were estimated with the nonlinear iterative method of least squares. The value of the coefficient of determination (r2) and residual analysis were employed to verify the appropriateness of fit. The coefficient b values were tested with respect to isometry (β=3) using a tα1,0.05 test. The values of coefficient b ranged from 2.377 to 3.538. There is a tendency for positive allometry (b) in the sampled ichythyocenose.

Mobility and kinematic simulations of cyclically symmetric deployable truss structures

Based on the mechanism of four-fold rigid origami, this study proposes a type of deployable truss structures that consist of repetitive basic parts and retain full cyclic symmetry in the folding/deployment process. On the basis of the irreducible representations and the great orthogonality theorem, symmetry-adapted analysis using group theory is described to identify the symmetry of mobility and kinematic behavior. Equivalent three-dimensional pin-jointed frameworks are employed for the symmetric structures. To verify that the structures can be foldable while retaining their full symmetries, numerical simulations on a series of structures with different symmetries and geometries are carried out. An artificial damping is introduced to stabilize the nonlinear folding behavior with singularity. Symmetry-adapted mobility analysis reveals that the structures of this type can be continuously folded with one degree-of-freedoms. Numerical simulations using the nonlinear iterative method accurately predict the folding behavior, as the results agree very well with the theoretic value.

COMPUTER SIMULATION OF MAGNETIZATION FOR 3D ELLIPSOIDAL TORUS-SHAPED InAs/GaAs QUANTUM RINGS

In this paper we computationally investigate the magnetization for three-dimensional (3D) InAs/GaAs nanorings with different radii in an external magnetic field. Our simulation model includes: (i) the effective mass Hamiltonian in nonparabolic approximation, (ii) the position- and energy-dependent quasi-particle effective mass approximation, (iii) the finite hard wall confinement potential, and (iv) the Ben Daniel–Duke boundary conditions. The nonlinear iterative method is applied to solve the 3D problem. With the developed computer simulator, we find the magnetization for the 3D InAs/GaAs ring is a negative function and oscillates nonperiodically. The oscillation saturates when the applied magnetic filed is increased. This result provides an alternative for the nanoring energy shell structure study and is useful for spintronics applications.