This paper deals with an LQG control problem for input time delay systems using closed-loop identification. A virtual system is introduced to solve a spectral factorization, which does not include integral operator. The solution of the factorization is used as a prefilter of closed-loop identification. An iterative identification and control design method is applied and some numerical examples are shown.
A cooperative coecolutionary genetic algorithm (CCGA) to the dynamic facility layout problems (DFLP) is examined. The CCGA has two major features. Firstly, a multi-population approach is adopted. The entire solution is constructed by individuals picked up from each population which corresponds to layouts of a production period in DFLP. An individual's fitness value is calculated with the best individuals of the other populations so that the populations can co-evolve in a cooperative manner. Secondly, steady-state selection process is embedded in each population to promote the exploitation in the genetic search. Computer simulations on two benchmark problems are conducted. It is found that the CCGA outperforms the other GAs consistently.
We propose a method of information filtering for Web browsing based on a model of user's interests. We have already proposed Context-Sensitive Filtering (CSF) for browsing on CD-ROM encyclopedia, which follows up shifting user's interests in this case. We confirmed the effectiveness of CSF. However, it is not very effective for Web browsing. We assumed that one of the reasons is the difference of pages between the Web and CD-ROM encyclopedia. We describe improvements of modeling to estimate user's interests and filtering method by dividing Web pages. We confirmed the effectiveness of our filtering through an experiment to compare several filtering methods.
When the statistical data such as failure data, which are realizations of an i.i.d. random variable, are given, the histogram is often used to understand the underlying distribution property. In this paper, we propose a non-parametric algorithm to estimate the renewal function from the histogram. The estimation algorithm is based on the direct Rieman-Stieltzes integration method. Also, it can be improved in terms of estimation accuracy by applying the interpolation with the spline function or the radial basis function neural network. Finally, in numerical examples, we evaluate the proposed algorithm and its improved versions, and refer to the potential applicability of them.
Multi-robot systems have been introduced actively in heavy industry in order to increase the productivity. However, since the configuration of workpiece is complex due to multi-kind small lot production especially in shipbuilding and in multi-robot systems robots are disposed as densely as possible in a working area to get high productivity, collision between adjacent robots could occur. Because the collision prevents effective production, collision occurrence should be avoided. This paper reduces the problem of minimization of total welding time subject to collision/deadlock avoidance among multi-robots to a path optimization one, and solves it through genetic algorithm (GA). Its effectiveness is shown by numerical simulations with practical workpieces. Furthermore, a two-step GA algorithm is proposed, where the welding path of the maximal loaded robot is optimized first and then those of other robots are optimized.
Various scheduling methods have been proposed in order to minimize total flow time or total actual flow time, and thereby promote efficient production. However, such methods are not so effective to maximize company profit, given that requests from customers and the prices of products have grown widely diversified in recent years. In such a case, it must be determined whether the profit can be maximized when both flow times are minimized. This paper proposes an optimal scheduling method which maximizes total profit as a performance measure in a single machine model. Our computational experiments show the usefulness and characteristics of the proposed method.
A new 3D scanning device which consists of a hand-held 3D sensor head and a stereo camera, is developed. In the measuring process, the coordinates of observed points are computed relative to the 3D sensor head, and the 3D sensor head is located relative to the fixed stereo camera. The 3D coordinates of the measured object are reconstructed in the two-stage process. The unique two-stage method makes it possible to move the sensor head freely and to measure the whole shape of the object in one sequence, of scanning. In this paper, we describe the system structure, the principle of measurement, some examples of measurement and its accuracy.