Fine motion strategy in three-dimensional space using skill-based backprojection

The motion of manipulation in a task can be decomposed into several motion primitives called “skills.” Skill-based motion planning gives the possibility of performing tasks as skillfully as human beings do. On the other hand, the backprojection method performed in configuration space has often been used in fine-motion planning. This paper describes fine-motion planning in three-dimensional space using skill-based backprojection. Now that skill-based planning in three-dimensional space has been developed, it becomes possible to plan manipulation motions like the behavior of the human hand. This work was presented, in part, at the Second International Symposium on Artificial Life and Robotics, Oita, Japan, February 18–20, 1997.     

Analysis of atmospheric electric field variation signals using digital natural observation method

As the atmospheric electric field always fluctuates, its observed waveforms are very complicated. It is important to detect the characteristic variation from the observed signals and determine its cause. The natural observation method is adequate for analyzing such nonperiodic signals as the atmospheric electric field signals. In this method the aspectum is proposed as the quantity to estimate the instantaneous power. In this study signal processing by the aspectum was applied to signals of atmospheric electric field variation. It was clarified that a strong correlation exists between the instantaneous fluctuations of atmospheric electric field and the wind speed in the convenient meteorological environment. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 155(1): 27–34, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20302     

A novel PWM scheme of voltage source inverters based on space vector theory

Contents A novel PWM scheme which can considerably reduce harmonic currents is proposed. It is explained analytically that the harmonic currents depend on the amplitude and phase angle of the reference voltage vector, the inverter output voltage vectors used in a switching period, and the sequence of these output voltage vectors. In the novel PWM scheme, the switching sequence is selected so that the harmonic currents are minimum. An experimental system which generates the PWM patterns by software at real time is constructed. Compared with the conventional sinusoidal PWM scheme, it is confirmed that the current ripple is decreased and the spectrum is shifted and dispersed to a higher frequency region.

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Ein neues Modulationskonzept für Wechselrichter mit eingeprägter Spannung

Übersicht Es wird ein neues Modulationskonzept vorgeschlagen, mit dem die Oberschwingungsströme beträchtlich herabgesetzt werden können. Wie analytisch gezeigt wird, hängen diese von Amplitude und Phasenwinkel des Zeigers der Referenzspannung, der Wechselrichter-Ausgangsspannung in einer Schaltperiode und der Abfolge der Zeiger dieser Ausgangsspannung ab. Nach dem neuen Konzept wird die Schaltfolge so gewählt, daß sich ein Minimum der Oberschwingungsströme ergibt. In einer Versuchseinrichtung wird das Pulsmuster durch Software in Echtzeit generiert. Im Vergleich mit der konventionellen Sinusbewertung bestätigt sich eine Verminderung der Welligkeit und eine Verschiebung des Oberschwingungsspektrums in den Bereich höherer Frequenzen.

     

De-t-butylation of t-butylphenols over dealuminated zeolites in liquid-solid system

Liquid-solid phase de-t-butylation of p-t-butylphenols was carried out over original and dealuminated zeolites to determine the effect of catalyst pore size and acidity on the reaction rate and catalyst fouling rate. The de-t-butylation rate over the original zeolites was mainly dependent upon their micro pore sizes. Although the dealumination by acid leaching decreased strong acid sites, the de-t-butylation rate over dealuminated HY zeolite was higher than that on the original zeolite. The present dealumination is a useful method to prepare an acid catalyst for de-t-butylation in a liquid-solid system.     

Repeated temperature modulation epitaxy for p-type doping and light-emitting diode based on ZnO.

Since the successful demonstration of a blue light-emitting diode (LED), potential materials for making short-wavelength LEDs and diode lasers have been attracting increasing interest as the demands for display, illumination and information storage grow. Zinc oxide has substantial advantages including large exciton binding energy, as demonstrated by efficient excitonic lasing on optical excitation. Several groups have postulated the use of p-type ZnO doped with nitrogen, arsenic or phosphorus, and even p-n junctions. However, the choice of dopant and growth technique remains controversial and the reliability of p-type ZnO is still under debate. If ZnO is ever to produce long-lasting and robust devices, the quality of epitaxial layers has to be improved as has been the protocol in other compound semiconductors. Here we report high-quality undoped films with electron mobility exceeding that in the bulk. We have used a new technique to fabricate p-type ZnO reproducibly. Violet electroluminescence from homostructural p-i-n junctions is demonstrated at room-temperature.     

A new generation of modems for power efficient radio systems

A new class of generalized intersymbol-interference and jitter-free (GIJF) modulated signals is introduced. Computer simulation and hardware experimental research results demonstrate that our proposed new generation of signals and modulators leads to significant performance improvements in non-linearly amplified broadband radio systems. For increased power efficiency, non-linear amplification is required in most commercial satellite and terrestrial microwave systems. In particular, we demonstrate that the 3 dB envelope fluctuation of currently used offset raised-cosine overlapped QPSK systems is reduced to 0-5 dB, and that the BER performance is improved by approximately 1 dB. These significant technical performance advantages are expected to lead to more economical implementations of digital transmission systems.     

Ti-Containing Silsesquioxane Gels with Tunable Porosity: Preparation and Catalytic Activity for the Epoxidation of Cyclooctene by Aqueous Hydrogen Peroxide

Novel Ti-containing silsesquioxane gel catalysts were prepared by the hydrosilylative condensation of Ti-containing silsesquioxanes together with cubic silsesquioxanes and spherosilicates. The porosity of gels was controlled by changing the composition and the mixing order of the starting materials. Both porous and nonporous gels were found to act as excellent heterogeneous catalysts towards the selective epoxidation of cyclooctene by the use of aqueous hydrogen peroxide as an oxidant.     

Efficiency enhancement in the conversion into the magnetostatic mode utilising a specially designed coiled transducer

The letter describes a specially designed coiled transducer for the magnetostatic mode. The conversion loss of the magneto-static-mode delay line provided with the proposed transducer has been found reduced down to 10.5 dB at L band.     

An interactive system for constructing cat''s cradle string diagram using GA

In many method of the cat's cradle string diagram processing in use today, there is no a strong emphasis on user interaction. This paper discusses a method for constructing cat's cradle string diagram in 2-D. The method uses a string representation and processing in 2-D which preserves the topology characteristics of the string diagram and also uses a small data volume. The inputted string diagram is transformed onto its cat's cradle string diagram by geometric transformation and GA. The method allows the user to interactively construct a cat's cradle string diagram. Three operations are used for constructing cat's cradle diagram, they are pull (over and under), release and exchange. An implemented program executed some shapes of cat's cradle for verifying the method.