La 1−x Sr x CuOS  (x=0, 0.05) thin films prepared by radio-frequency sputtering were found to have high optical transmission (⩾70%) at the visible and near-infrared wavelengths and an energy gap of about 3.1 eV. The dc electrical conductivities of x=0 and 0.05 thin films at room temperature were 1.2×10−2 and 2.6×10−1 S cm−1, respectively. The Seebeck coefficients of these samples were positive, indicating that p-type electrical conduction is dominant in these materials. A sharp photoluminescence peak, probably originating from an interband transition, was observed at the optical absorption edge. The present study demonstrates that LaCuOS is a promising transparent p-type semiconductor for optoelectronic applications. Moreover, our material design, based on chemical modulation of the valence band, was successfully extended to oxysulfide systems.

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A number of positzoning identification techniques have been used for mobile robots. Dead reckoning is a popular melhod, but zs not relzable when a robot trave h long distances or over an uneven surface because of uariations zn wheel diameter and wheel slzppage. The landmark method, which estzmates the current posiiion relaizae to landmarks, cannot be used an an unckarted cni:i.ronment. W e propose a new method called "Coopcrclti,ire Positioning wzth Multzple Robots." POT cooperai.ii:e positioning, we divide the robois into imo groups, .A and B. One group, say A , remains stationary and acts LIS a landmark while group B moves. The moving group R th.en slops and acts as a landmark for group .A. Thzs "dance" is repeated untd the target roboi p osition are reuch.ed. Cooperahoe positioning h,as a far lo.wer accumulated positzoning error than dead reckonzng, and can work in th.ree-dimenstons which i s noi possible with dead reckonzng. Also, this meth.od has rnherent landmarks and therefore works zn uncharted environments. This paper discusses the positioning acc'uraq of our meth.od wzth error variances ~O T an example milh three mobale robots.

There is growing interest in heat pumps based on materials that show thermal changes when phase transitions are driven by changes of electric, magnetic or stress field. Importantly, regeneration permits sinks and loads to be thermally separated by many times the changes of temperature that can arise in the materials themselves. However, performance and parameterization are compromised by net heat transfer between caloric working bodies and heat-transfer fluids. Here we show that this net transfer can be avoided-resulting in true, balanced regeneration-if one varies the applied electric field while an electrocaloric (EC) working body dumps heat on traversing a passive fluid regenerator. Our EC working body is represented by bulk PbSc 0.5 Ta 0.5 O 3 (PST) near its first-order ferroelectric phase transition, where we record directly measured adiabatic temperature changes of up to 2.2 K. Indirectly measured adiabatic temperature changes of similar magnitude were identified, unlike normal, from adiabatic measurements of polarization, at nearby starting for Electrocaloric cooling cycles in lead scandium tantalate with true regeneration via field variation

The paper addresses some of the fundamental problems of energy efficiency, design, and adaptive gait control of quadru ped walking vehicles. The design principle of a leg called a gravitationally decoupled actuator ( GDA) is shown to be indispensable for realizing energetically efficient walking mo tion. A novel mechanism, the three-dimensional Cartesian- coordinate pantograph ( PANTOMEC), which follows the GDA principle and has a lightweight structure, is introduced. A constructed quadruped walking vehicle model is then de scribed : the walking vehicle has the PANTOMEC leg mecha nisms, eight tactile sensors and a posture detector, and is hierarchically controlled by a microcomputer. Comparatively high energy efficiency and a certain degree of terrain adapt ability is demonstrated. It is thus shown that a practical walking vehicle can be designed using the proposed method. The adaptive gait control problem is formalized, and an algorithm for terrain-adaptive gait control is presented. By computer simulation, it is shown that the algorithm produces an efficient gait while avoiding "deadlock" positions in nego tiating terrain. The algorithm is shown to be applicable for the control of future quadruped walking vehicles with visual sensors.