Eectiv Eness Research Articles

Subsonic and Transonic Jet Control with Cross-Wire

Cross-wire eectiv eness for subsonic and sonic jet control is reported in this paper. Mach 0.4, 0.6, 0.8 and 1.0 axisymmetric jets from a convergent nozzle with cross-wire along a diameter at the exit were studied. The cross-wire was found to be eectiv e in promoting jet mixing right from the nozzle exit, at all Mach numbers. For the underexpanded sonic jet at NPR 3, 5 and 7, the cross-wire inuenced the core and the shock cells, causing signican t reduction of core length and weakening of the shocks at all levels of underexpansion. The jets from the nozzle with cross-wire spread faster in the direction normal to the cross-wire.

JHomogenizer: a computational tool for upscaling permeability for flow in heterogeneous porous media

Porous media have properties with heterogeneities on several length scales. It is possible to use upscaled or homogenized models in which the eectiv e properties of the medium vary on a coarse scale suitable for ecien t computation, but that accurately capture the inuence of the ne-scale structure on the coarse-scale properties of the solution. Numerical homogenization has proven its value in studying multiphase subsurface o w in heterogeneous porous media in geohydrology and petroleum engineering applications. We are concerned with approximating eectiv e permeability for such problems using conforming and mixed nite elements methods. This paper presents an OOP (Object Oriented Programming) approach for design of numerical homogenization programs. General organization of the developed software system, called JHomogenizer, is given which includes the solver and the pre/post processors with a user-friendly Graphical User Interface (GUI). It currently includes v e functional modules to compute eectiv e permeability and simples code for computing solutions for o w in porous media. Examples with graphical output are used to illustrate some functionalities of the program. The software is freely available and the open architecture of the program facilitates further development and adaptation to suit specic needs easily and quickly. Moreover, the user interface has proven to be easy to use and exible. A series of numerical examples demonstrates the eectiv eness of the methodology for two-phase o w in heterogeneous reservoirs.

Oscillation Results for Linear Matrix Hamiltonian Systems

Some new criteria have been established for the oscillation of the linear matrix Hamiltonian system X 0 = A(t)X + B(t)Y; Y 0 = C(t)X A (t)Y under the hypothesis: A(t), B(t) = B (t) > 0 and C(t) = C (t) are n n real continuous matrix functions on the interval (t0;1) (t0 > 1 ). Our results are dieren t from most known ones in the sense that they are given in the form lim supt!1 g( ) > const: rather than lim supt!1 1( ) = 1, where g is a positive linear functional on the linear space of n n matrices with real entries. Our results improve some previous ones. Two examples are worked out to illustrate the eectiv eness of our results. AMS (MOS) Subject Classication. 34A30, 34C10.

2505 塗装ラインを含んだ混合品種組立ラインの最適製品投入順序付け(S77-1 生産システムの新展開-基礎(1),S77 生産システムの新展開(基礎理論を中心に))

In order to keep production balance at a mixed-model assembly line and a painting line, large WIP(Work- In-Process) inventories are required between two lines. To increase the eciency of line handling through reducing the inventories under this circumstance, this paper concerns with a sequencing problem for a mixed-model assembly line that includes a painting line where the uncertain elements regarding the defective products exist. Then, we formulate a new type of the sequencing problem minimizing the line stoppage time and the idle time with forecasting the supply time of the products from the painting line. Finally, we examine the eectiv eness of the proposed sequencing through computer simulations.

自由度が制限された2指ハンドによる転がり接触を用いた対象物の把握・操りと接触点の同時制御

This paper considers simultaneous control of grasp/manipulation and contact points of an object with the pure rolling contact by two-ngered robot hand. We consider the case where the number of the degrees of freedom (DOF) of each nger is constrained. First, we derive a relationship between the rolling velocity and the motion of the ngers and the object, which determines the number of the DOF of the system. Second, we provide explicit expressions of the contact force and the motion of the ngers and the object, which can be directly used for the simultaneous control. Utilizing the results, we provide a general formulation of a linearizing compensator for the simultaneous control. Controlling the contact points can be realized by making the rolling velocity follow the appropriate trajectory with the nonholonomy of rolling. A numerical example shows the eectiv eness of the method.

ステレオカメラを用いた頭部位置・姿勢計測とレーザレンジファインダを用いた自己位置・姿勢計測の拡張現実感への応用

Augmented Reality(AR) allows the user to see the real world, with annotations superimposed on the real scene. Therefore, it is eectiv e to guide a user intuitive way. In this paper, we describe an application of head tracking method using a stereo camera pair and localization method using a laser range nder to AR. It is important to measure the position and the orientation of a user accurately in order to build an AR system. In our approach, the head position and orientation of the user is measured by a pair of stereo cameras, and the position of the user is estimated by a laser range nder. We conducted experiments to evaluate the usefulness of these methods for AR, and the eectiv eness was conrmed. Finally we developed an AR-based guidance system for a wheelchair using both measurement methods. An experiment to guide the user was conducted and the usability of this system was conrmed.

An Analytical Criterion for Stability Boundaries of Non-Autonomous Systems Based on Melnikov's Method

y This paper proposes an analytical criterion for stability boundaries of non-autonomous systems. The criterion can analytically enlarge the conservative stability limits obtained by the classical Lyapunov's direct method almost up to the exact stability boundaries even for non-autonomous systems. It is based on the Melnikov's method which estimates homoclinic intersections in the dynamical systems theory. The denition of the criterion has strong advantages in its easy and quick estimation of the stability, compared with the numerical integration of the non-autonomous systems. The eectiv eness is conrmed in its application to an electric power system with dc transmission under periodic swing.

多関節ロボットアームのトルクと速度制限下での許容軌跡内の高精度制御法

High speed and high accurate control performance is required for industrial robot arms. The research is aimed at high accurate control of industrial articulated robot arms with trajectory allowance under torque and speed constraints. The proposed method is based on nonlinear separation that decomposes the nonlinear dynamics from the nonlinear static parts and linear dynamic part. Controller was constructed for separation of trajectory generation and taught data generation, and it could be achieved perfect performance under the speed and torque constraints imposed by the hardware of robot arm. The eectiv eness of the proposed method was assured by experimental results of an actual articulated robot arm.

Learning both a World Model and Navigation Paths in an Unknown Environment

This paper presents a new method for mobile robot navigation in an un- known world. The parti-game learning approach is used to construct a world model, and to learn to navigate from a starting position to a known goal region. The navigation architecture then integrates a new approach, based on the application of the Fuzzy ART neural architec- ture, for on-line map building from actual sensor data. This leads to an improved world model, which is then used to introduce a predictive on-line trajectory ltering method resulting in a new and more eectiv e navigation approach. It is assumed that the robot knows its own current world location, is able to perform sensor-based obstacle detection (not avoidance), and straight-line motions. Simulation and real-robot results obtained with a Nomad 200 mobile robot will be presented demonstrating the eectiv eness of the discussed methods. Quanti- tative results will demonstrate (1) the exploration and planning improvements of the new navigation approach, and (2) that the constructed world model (original or improved) is gen- eral purpose in the sense that its usefulness is not restricted to be used on learning a particular path, but is valuable for learning paths with dieren t (Start,Goal) pairs.

近似線形化を用いた倒立振子の制御

SUMMARY : In this paper, taking the inverted pendulum as an example of nonlinear systems which are not exactly linearizable, we give a controller design method for the system based on the approximate linearization. In the method, we try to suppress the eect of the higher order residual terms in choosing the new coordinate for the approximate linearization. Furthermore, we show its eectiv eness by experiments.