LC GRIN lens mode with wide viewing angle for rotatable 2D/3D tablet

To widen the vertical and horizontal angular ranges where the lens performs well, the off‐axis performance of a liquid crystal gradient index (LC GRIN) lens is analyzed by the combined simulation system of an LC director simulator and a ray‐tracing simulator. We found that the angular difference between an LC alignment direction and an electrode array direction of the LC GRIN lens is one of significant parameters, and detailed conditions of structure are established. The measurement result shows that the developed structure reduces the degradation ratio in a luminance profile from 61% to 3.2%. We have applied a user tracking system for the rotatable 3D display, equipped with a detection of a panel orientation and a face position. As a result, we have developed a rotatable 2D/3D tablet whose 3D viewing azimuth angle is over 30° in both landscape and portrait orientations.     

A master-slave control system for a semi-autonomous underwater vehicle-manipulator system

Underwater vehicle-manipulator systems (UVMS) are expected to play an important role in ocean exploration. It is considered that UVMS will be operated by both automatic and manual control. We have proposed an automatic control method. In this article, we propose a master-slave system for a UVMS. The effectiveness of the proposed master-slave control system is demonstrated by using a floating underwater robot with a 2-link manipulator.     

Cooperative manipulation of a floating object by some space robots with joint velocity controllers: application of a tracking control method using the transpose of the generalized Jacobian matrix

We have studied the cooperative manipulation of floating object by several space robots. For these cooperative motions, we have reported that a tracking control method using the transpose of the generalized Jacobian matrix (GJM) can be utilized for robots with joint torque controllers. For cooperative motions by some robots with joint velocity controllers, we proposed a tracking control method using the transpose of the GJM. Simulation results show the effectiveness of the proposed control method.     

Polygon visibility ordering via Voronoi diagrams

Visibility determination is one of the oldest problems in computer graphics. The visibility, in terms of back-to-front polygon visibility ordering, is determined by updating a priority list as the viewpoint moves. A new list-priority algorithm, utilizing a property of Voronoi diagrams, is proposed in this paper. The operation is in two phases. First, in a pre-processing phase the scene is divided into Voronoi cells. A sub-list associated with each cell contains references to those polygons that intersect with it. The polygons are assigned a fixed set of view-independent priority orders within the cluster. Last, an interactive phase sorts the clusters according to the depth value of each Voronoi site. The most time-consuming work is performed during the pre-processing phase that only has to be executed once for the scene. Since all the polygons in a cell are pre-computed to obtain the fixed priority order within the cluster, a relatively simple task is left in the interactive phase, which is only to sort the clusters repeatedly when the viewpoint is changed. This method contains performance benefits that make it better shaped than previous BSP based methods.     

Digital RAC with a disturbance observer for underwater vehicle-manipulator systems

Most control methods of underwater vehiclemanipulator systems (UVMS) are based on the computed torque method that is used for underwater robotic vehicles. We have proposed a resolved acceleration control (RAC) method for UVMS. In this article, we propose a disturbance compensation control method for both vehicle and manipulator based on the RAC method. Experimental results using an underwater robot with a vertical planar 2-link manipulator show that the proposed control method has good control performance.     

Variational Bayes solution of linear neural networks and its generalization performance

It is well known that in unidentifiable models, the Bayes estimation provides much better generalization performance than the maximum likelihood (ML) estimation. However, its accurate approximation by Markov chain Monte Carlo methods requires huge computational costs. As an alternative, a tractable approximation method, called the variational Bayes (VB) approach, has recently been proposed and has been attracting attention. Its advantage over the expectation maximization (EM) algorithm, often used for realizing the ML estimation, has been experimentally shown in many applications; nevertheless, it has not yet been theoretically shown. In this letter, through analysis of the simplest unidentifiable models, we theoretically show some properties of the VB approach. We first prove that in three-layer linear neural networks, the VB approach is asymptotically equivalent to a positive-part James-Stein type shrinkage estimation. Then we theoretically clarify its free energy, generalization error, and training error. Comparing them with those of the ML estimation and the Bayes estimation, we discuss the advantage of the VB approach. We also show that unlike in the Bayes estimation, the free energy and the generalization error are less simply related with each other and that in typical cases, the VB free energy well approximates the Bayes one, while the VB generalization error significantly differs from the Bayes one.     

Hardware system of the Earth Simulator

The Earth Simulator (ES), developed under the Japanese government’s initiative “Earth Simulator project”, is a highly parallel vector supercomputer system. In this paper, an overview of ES, its architectural features, hardware technology and the result of performance evaluation are described.

In May 2002, the ES was acknowledged to be the most powerful computer in the world: 35.86 teraflop/s for the LINPACK HPC benchmark and 26.58 teraflop/s for an atmospheric general circulation code (AFES). Such a remarkable performance may be attributed to the following three architectural features; vector processor, shared-memory and high-bandwidth non-blocking interconnection crossbar network.

The ES consists of 640 processor nodes (PN) and an interconnection network (IN), which are housed in 320 PN cabinets and 65 IN cabinets. The ES is installed in a specially designed building, 65 m long, 50 m wide and 17 m high. In order to accomplish this advanced system, many kinds of hardware technologies have been developed, such as a high-density and high-frequency LSI, a high-frequency signal transmission, a high-density packaging, and a high-efficiency cooling and power supply system with low noise so as to reduce whole volume of the ES and total power consumption.

For highly parallel processing, a special synchronization means connecting all nodes, Global Barrier Counter (GBC), has been introduced.     

Organic LED full-color passive-matrix display

Abstract— A full-color 5.2-inch 1/4-VGA passive-matrix organic LED display has been developed, adopting selective deposition for the different emitting materials. The display features 320 (×3) × 240 pixels with an equivalent pixel size of 0.33 × 0.33 mm, white peak luminance of over 150 cd/m², and power consumption of 6 W.     

Observations of bound Tween80 surfactant molecules on single-walled carbon nanotubes in an aqueous solution

The slow diffusion of Tween80 surfactant molecules in a single-walled carbon nanotube (SWCNT) aqueous dispersion was directly observed using the pulsed field gradient nuclear magnetic resonance method. The slow diffusion of Tween80 molecules was attributed to the strongly adsorbed molecules on the SWCNTs in the aqueous dispersion. The amount of bound Tween80 molecules was estimated to be approximately 12% of the total amount of Tween80 molecules, contributing to the stability of the SWCNT aqueous dispersion. Using dynamic light scattering and total organic carbon measurements, this SWCNT/Tween80 aqueous dispersion was found to be very stable for at least 3 weeks. The observed zeta potentials of this SWCNT dispersion are between −10 and 0 mV, indicating that the stability of the SWCNTs in the Tween80 solution was maintained by steric interactions between the small amount of adsorbed Tween80 molecules on the SWCNTs, while the effect of electrostatic interactions between adsorbed Tween80 was minimal. This proposed method to investigate the amount of bound Tween80 molecules on SWCNTs has potential benefits in the field of the production of functional materials and nano-toxicity assessments.