In this paper, we investigate influences of the network delay on haptic cooperative work in a networked virtual environment by experiment. In the work, two users carry an object cooperatively in a networked maze system by manipulating haptic interface devices. We handle two carrying methods in our experiment. In one method, the two users hold the object. In the other method, one user holds the object and the other user pushes it. We measure the operation time and reaction force, and we compare them between the two methods. Experimental results demonstrate that the former method has smaller average operation time than the latter method, but the average reaction force is larger in the former.

In this paper, we deal with four types of stabilization control for a remote robot system in which a user remotely operates an industrial robot arm with a force sensor by using a haptic interface device while watching video. The four types of control include the stabilization control with filters, the stabilization control by viscosity, the reaction force control upon hitting, and the switching control. To make a comparison of them quantitatively, we carry out the quality of experience (QoE) assessment in which we treat work of pushing four balls with different softness by a metal rod attached to the tip of the industrial robot arm.

This study proposes distributed control for link failure based on loops in a network to conduct local management. A loop can be expressed by a set of links, which is called a tie-set. More local and high-speed recovery is considered to be possible if failure is resolved within some tie-sets. This paper introduces the tie-set concept first, and then describes the distributed algorithms for link failure. Experiments to compare against RSTP are also conducted.

Customers of telecommunication services are strongly interested in the service outage time. In order to respond to these requirements, the following measures are now being investigated. The first is to keep the frequency of outages of which the duration time exceeds a certain length under a certain level, and the second is to inform the customers of the residual outages time when a service outage occurs. The evaluation and design method of the frequency of long outages has been developed in order to achieve the first objective. The prediction method of the residual outage time has also been developed for the second objective. Moreover, the software tool for assisting one to carry out those measures are also being developed. The outline of those evaluation and prediction methods and the software tool is described.

This paper is concerned with a response time of an information network. After introducing fundamental quantities of an information engine, we define three types of network response time; transfer, processing and operating response time, and present important properties associated with an information network in minimizing them.>

Harmonic distortion of distributed feedback laser diodes (DFB-LDs) for analog transmission systems is investigated. It is shown that, under a modulation frequency of less than 1 GHz, the harmonic distortion depends on the nonlinearity of the light output power-current (P-I) curve under the continuous wave (CW) condition, which is determined by the coupling constant kappa L, and that the distortion can be minimized at kappa L approximately 1. A 1.3 mu m wavelength InGaAsP DFB-PPIBH (p-substrate partially inverted buried heterostructure) LD and its module, with low distortion by the control of a coupling constant, have been developed.>