Measuring and reducing axial motion of flat belt by finite element analysis

A simulation method for estimating and reducing axial motion of flat belt is developed by using a commercial finite element (FE) code, MARC. The simulated results of the axial motion rate have good agreement with the experimental ones. This research further shows that the axial motion of flat belt can effectively be reduced by setting an added steering roller to center position of the belt loosen span. Observing the deflected configuration of belt centerline and its expanded shape on two roller surfaces, we find a phenomenon that the belt wraps on the roller surface spirally and rotates with the roller without slippage. The mechanism of the belt axial motion is clarified in this paper.     

Development of a Cleaning Robot System with Cooperative Positioning System

For the development of an automatic floor cleaning robot system, an accurate positioning method in unstructured and dynamically changing environments is indispensable. Dead reckoning is a popular method, but is not reliable for measurement over long distances especially on uneven and slippery floors due to the accumulation error of wheel diameter and slippage. The landmark method, which estimates current position relative to landmarks, cannot be used in an uncharted and an unfamiliar environment. We have proposed a new method calledCooperative Positioning System (CPS). The main concept of CPS is to divide the robots into two groups, A and B where group A remains stationary and acts as a landmark while group B moves, then group B stops and acts as a landmark for group A. This process is repeated until the target position is reached. CPS has a far lower accumulation of positioning error than dead reckoning, and can work in three-dimensions. Also, CPS has inherent landmarks and therefore works in uncharted environments. In previous papers, we have introduced the prototype CPS machine models, CPS-I and CPS-II and demonstrated high performance as a positioning system in an unknown and uneven environment. In this paper, we report on the third prototype CPS model, CPS-III, that is designed specifically as an automatic floor-cleaning robot system, and the results of a floor cleaning experiment. In this system, we categorize these robots fortwo tasks, that is, an accurate positioning task achieved with 3 robots using the CPS strategy, and a floor-cleaning task executed by an omni-directional vehicle, so as to improve the efficiency of the floor-cleaning system. Experiments show that these robots can perform a floor-cleaning task in a corridor within a positioning error of 140.8 mm even after robots move over a distance of 101.7 m.     

A Content-Addressable Memory Using “Switched Diffusion Analog Memory with Feedback Circuit”

For the purpose of realizing a new intelligent system and its simplified VLSI implementation, we propose a new nonvolatile analog memory called switched diffusion analog memory with feedback circuit (FBSDAM). FBSDAM has linear writing and erasing characteristics. Therefore, FBSDAM is useful for memorizing an analog value exactly. We also propose a new analog content-addressable memory (CAM) which has neural-like learning and discriminating functions which discriminate whether an incoming pattern is an unknown pattern or a stored pattern. We design and fabricate the CAM using FBSDAM by means of the 4 m double-poly single-metal CMOS process and nonvolatile analog memory technology which are developed by us. The chip size is 3.1 mm×3.1 mm. We estimate that the CAM is composed of 50 times fewer transistors and requires 70 times fewer calculation steps than a typical digital computer implemented using similar technology.     

Sodium cooled small fast long-life reactor “4S”

CRIEPI and Toshiba Corp. have been exploring to realize a small-sized nuclear reactor for the needs of dispersed energy source and multi-purpose reactor. A conceptual design of 4S (Super-Safe, Small and Simple) reactor is proposed to meet the following design requirements: (1) All temperature feedback reactivity coefficients including whole core sodium void reactivity are negative; (2) The core integrity is secured against all anticipated transient without reactor scram; (3) No emergency power nor active mitigating system is required; (4) The reactivity core lifetime is more than 10 years. The 4S reactor is a metallic fueled sodium cooled fast reactor. A target of an electrical output is 10–50 MW. A remarkable feature of 4S is that its reactivity is not controlled by neutron absorber rods but by neutron reflectors to cope with a long core lifetime and a negative coolant void reactivity.

This study includes a design consideration of 4S. Design discussions are mainly focused on various core designs to meet above requirements. A tall core active height is adopted to gain long core lifetime. An averaged fuel burn-up is tried to be increased up to 100 GWd/ton from a point of economic view. The reference 4S designs are 10 MWe (30 years core lifetime) and 50 MWe (10 years core lifetime).     

Thin-Layer Photografting as a Method of Polymer Surface Modification

A. Importance of Surface Properties

When any solid material, either organic or inorganic, is to be used, surface properties of the material often determine the value as a practical usable material. All solid materials having definite shapes are surrounded by other materials, and hence interfacial phenomena should be taken into account. Surface properties are as important as such bulk properties as tensile strength, elongation, Young's modulus, and hardness. Furthermore, full utilization of bulk properties is often supported by surface properties. This is particularly the case of fiber, film, membrane, or others in which the surface area/volume ratio is large. Even when mechanical properties alone look important, as in the case of composite materials, interfacial phenomena in filler-matrix interactions are fundamental in determining the bulk properties.     

Crystal orientation of non-magnetic materials by imposition of a high magnetic field

From the view point of learning from the nature, the controlling of crystal orientation is accounted to be a major subject for materials processing. This paper reviews the researches on the crystal orientation by use of a high magnetic fieldand belongs to the category of researches for mimicking structures, namely the crystal orientation, which nature or livingbodies are forming. Regarding to the crystal orientation, several methods such as unidirectional solidification and epitaxial growth and so on have been developed hitherto. On the other hand the magnetization force that is familiar with the force to attract iron to a magnet, has been recognized to be effective even in non-magnetic materials when those are placed under a high magnetic field, which has become rather conveniently available by developing superconducting technologies in these days. In this paper, main results obtained when the imposition of a high magnetic field was accompanied to several materials processing such as electrodeposition, vaperdeposition, solidification, baking, slip-casting and precipitation, arereviewed from the view point of crystal orientation of non-magnetic materials.     

Mechanical design of walking machines

The performance of existing actuators, such as electric motors, is very limited, be it power-weight ratio or energy efficiency. In this paper, we discuss the method to design a practical walking machine under this severe constraint with focus on two concepts, the gravitationally decoupled actuation (GDA) and the coupled drive. The GDA decouples the driving system against the gravitational field to suppress generation of negative power and improve energy efficiency. On the other hand, the coupled drive couples the driving system to distribute the output power equally among actuators and maximize the utilization of installed actuator power. First, we depict the GDA and coupled drive in detail. Then, we present actual machines, TITAN-III and VIII, quadruped walking machines designed on the basis of the GDA, and NINJA-I and II, quadruped wall walking machines designed on the basis of the coupled drive. Finally, we discuss walking machines that travel on three-dimensional terrain (3D terrain), which includes the ground, walls and ceiling. Then, we demonstrate with computer simulation that we can selectively leverage GDA and coupled drive by walking posture control.     

Reconstruction of bone fenestration on mandiblar by the guided bone regeneration methods with beta-TCP/PLGC membranes

Guided Bone Regeneration (GBR) is a method for bone tissue regeneration. In this method, membranes are used to cover bone defects and to block the invasion of the surrounding soft tissues. It would provide sufficient time for the osteogenic cells from bone marrow to proliferate and form new bony tissues. In spite of the potential usefulness of this method, no appropriate materials for the GBR membrane have been developed. Here we design the ideal mechanical properties of the GBR membranes and created novel materials, which is the composite of beta-tricalcium phosphate (beta-TCP) and block copolymer of L-lactide, glycolide, and epsilon-caplolactone (PLGC). In the animal experiments with the use of the GBR membranes for large bone defects, we observed significant enhancement in the bone regeneration after 12 weeks implantation and proved the effectiveness of the materials.     

Production of single-chain variable fragment antibody (scFv) in fed-batch and continuous culture of Pichia pastoris by two different methanol feeding methods

This study examined the effects of two methods of methanol feeding, DO-stat and methanol concentration control, in fed-batch and continuous cultures of Pichia pastoris on cell growth and single-chain variable fragment antibody (scFv) expression. By maintaining the methanol concentration at 3.9 g l(-1) in fed-batch culture, a scFv concentration of 198 mg l(-1) was obtained. In continuous culture using both methanol feeding methods, the scFv concentration in the fermentation broth increased with a decreasing dilution rate. A maximum scFv concentration of 810 mg l(-1) at a dilution rate of 0.0094 h(-1) was obtained by maintaining the methanol concentration at 3.9 g l(-1). Although the specific methanol consumption rate was the same for both methods, the specific productivity of scFv was higher in methanol concentration control from 0.0094 to 0.049 h(-1) than it was in DO-stat control. Therefore, continuous culture with methanol feeding by the concentration control method shows promise for the industrial scale production of recombinant proteins by Pichia pastoris.