Inverse systems for reproducing linear functions of inputs

Most of the previous studies on inverse systems have treated only the case where all components of the input of the original system are recoverable. However, even when not all components are recoverable, there is still a possibility of reproducing part of the input. As a generalization of the inverse of a linear time-invariant dynamical system to include such cases, ‘α-integral F-inverse’ is proposed in this paper which reproduces the αth integral of a linear function Fu of the input vector u. A necessary and sufficient condition for the existence of an α-integral F-inverse is derived. A construction procedure of such an inverse is also given along with a numerical example.     

Conductance stopped-flow study of cationic polymerizations of p-methoxystyrene and styrene

Summary Conductance stopped-flow analysis on the initial phase of cationic polymerizations of p-methoxystyrene and styrene revealed rapid changes in conductance (within 20–50 ms) that were related to the initiation process. Initiation rate constants were obtained for CF₃SO₃H, CH₃COClO₄, and BF₃O (C₂H₅)₂ initiators in 1,2-dichloroethane at 30°C. They agreed closely with those determined by stopped-flow spectroscopy, and decreased with increasing monomer concentration.     

GaAs Schottky-barrier-diode frequency multipliers in 300 and 450 GHz bands

A 450 GHz-band tripler delivering an output power of ?11.2 dBm has been developed. A high-efficiency 300 GHz doubler whose conversion loss is 10.7 dB has also been developed. These efficient multiplications have been obtained by the use of GaAs Schottky-barrier diodes and thin-film integrated-circuit techniques.     

CO2-shielded arc as a high-intensity heat source

The characteristics of a CO₂-shielded arc are studied to evaluate its potential as a novel heat source for material processing, with lower costs and higher productivity than that of the tungsten–inert gas (TIG) arc. A double-gas-shielded system, using both CO₂ and an inert gas, is employed for the arc torch; this minimizes consumption of the tungsten electrode and gives arc stability equivalent to an argon TIG arc for 1800 s operation. The arc voltage of the CO₂-shielded arc is about 19 V for an arc current of 150 A and an arc gap of 3 mm, which is much higher than the 12 V obtained for an argon TIG arc. The CO₂ constricts the arc, resulting in an increase in the maximum heat flux density at the anode surface by a factor of about 10 relative to the TIG arc. The penetration depth of stainless steel melted by the CO₂-shielded arc is much larger than that for the argon TIG arc. It is concluded that the greater heating power of the CO₂-shielded arc, which is due to the greater arc constriction, in turn a consequence of the greater specific heat of CO₂, should lead to a large increase in material processing productivity.     

Motion capture from demonstrator's viewpoint and its application to robot teaching

In this paper, we propose a kind of “teaching by demonstration” method, aiming at its application to humanoid robots at home in the future. The demonstrator's motion is captured by a pair of stereo cameras mounted on his/her head, locating very close to his/her eyes. By tracking the landmarks attached to the demonstrator's hand and the working environment, one can estimate not only the demonstrator's hand motion but also his/her head motion, which can be used for the active vision system. Experimental result shows the effectiveness of the proposed framework. © 2005 Wiley Periodicals, Inc.     

Numerical investigation of production behavior of deep geothermal reservoirs at super-critical conditions

Numerical simulations have been performed to predict pressure transients in deep geothermal reservoirs at sub- and super-critical temperatures. First, pressure drawdown and buildup tests of reservoirs with different initial conditions were simulated. The calculated pressure responses are dominated by non-linear changes of fluid kinematic viscosity and compressibility. The pressure of a super-critical zone is shown to cause complex behavior. Short- and long-term production tests in both unbounded and bounded reservoirs were then simulated. Unbounded and bounded reservoirs exhibit very similar short-term production behavior near or above the critical temperature (375–400°C). Unbounded reservoirs of low transmissivity (kh = 1 darcy-meter) exhibit long-term production behavior that depends on whether the reservoir is sub-critical (300–375°C) or super-critical (400°C); substantial increases in flowing enthalpy and declines in feedpoint pressure occur at early times in the super-critical reservoir.