Web-Based Robotics Laboratory

In the education world, the number of web-based system is growing substantially in the past few years. Many web-based teaching tools has been developed to help students expand his knowledge. This paper presents a web-based laboratory to augment learning experiences in the field of robotics. The designed laboratory consists of a robotic arm with laser pointer, projection platform and web-based interface. The laboratory is used to learn about inverse kinematics and forward kinematics problems. Students enter the input parameters through web interface, server calculate output parameters and sent it to the robot. The web interface displays the movement result and turn on the laser pointer to the projection field. Preliminary testing concerning interface usability, access control mechanism and command queueing shows that the system working as expected.

STRIPE PATTERNS IN A MODEL FOR BLOCK COPOLYMERS

We consider a pattern-forming system in two space dimensions defined by an energy [Formula: see text]. The functional [Formula: see text] models strong phase separation in AB diblock copolymer melts, and patterns are represented by {0, 1}-valued functions; the values 0 and 1 correspond to the A and B phases. The parameter ε is the ratio between the intrinsic, material length-scale and the scale of the domain Ω. We show that in the limit ε → 0 any sequence uε of patterns with uniformly bounded energy [Formula: see text] becomes stripe-like: the pattern becomes locally one-dimensional and resembles a periodic stripe pattern of periodicity O(ε). In the limit the stripes become uniform in width and increasingly straight. Our results are formulated as a convergence theorem, which states that the functional [Formula: see text] Gamma-converges to a limit functional [Formula: see text]. This limit functional is defined on fields of rank-one projections, which represent the local direction of the stripe pattern. The functional [Formula: see text] is only finite if the projection field solves a version of the Eikonal equation, and in that case it is the L2-norm of the divergence of the projection field, or equivalently the L2-norm of the curvature of the field. At the level of patterns the converging objects are the jump measures |∇uε| combined with the projection fields corresponding to the tangents to the jump set. The central inequality from Peletier and Röger, Arch. Rational Mech. Anal.193 (2009) 475–537, provides the initial estimate and leads to weak measure-function pair convergence. We obtain strong convergence by exploiting the non-intersection property of the jump set.

Hyperglobal Interactions in Perception of Stereoscopic Transparency

A method has been developed (1) to measure limitations of human observers in perception of visual scenes containing a transparent surface, and (2) to study computational stages underlying stereoscopic transparency perception. Observers viewed random-dot stereograms of overlapping plane and cylindrical surfaces and had to distinguish between two orientations of the cylindrical surface under conditions of strict depth fixation control. Dot density of the transparent plane was increased at various intersurface depth separations until identification of cylinder orientation became random (limiting density). Limiting density dramatically decreased as depth separation between the surfaces grew, and this basic relationship could not be accounted for either by higher severity of matching with larger dot densities or by the ability of a denser surface to pull vergence to its depth. The basic relationship persisted with opposite contrast polarities of plane and cylinder dots, which suggests that competitive interactions between the surfaces occur as a separate process from binocular matching at each surface [Harris and Parker, 1995 Nature (London)374 808 – 811]. Thus, successive computational stages of matching and intersurface interaction characterising stereoscopic hyperglobality may be distinguished. We also found a facilitating role of intersurface brightness difference and a near — far asymmetry of the basic limiting density versus depth separation relationship with reversed surface positioning. We suggest a scheme of cortical inhibitory connections that agrees with the concept of disparity gradient limit and predicts performance similar to that reported. In the scheme, each activated unit produces a suppression zone in the disparity projection field so that lateral extension of the inhibition grows with binocular disparity.