Defection-free exchange mechanisms based on an entry fee imposition

We propose a safe exchange mechanism involving indivisible goods and divisible goods. A typical situation is an exchange involving goods and money in a person-to-person trade in an Internet auction. Although the Internet and agent technologies have facilitated world-wide trade, we sometimes encounter risky situations, such as fraud, in the process of exchanges involving goods and money. This problem is becoming more serious with the growing popularity of person-to-person trade. One of the reasons why fraud is becoming widespread is that obtaining a new identifier in a network is cheap. This makes it almost impossible to exclude malicious agents from trade. One solution is to impose an entry fee. However, if the entry fee is too high, it will discourage newcomers from starting deals. To resolve the conflict between safety and convenience, we developed three exchange mechanisms that can guarantee against defection from a contract. Two of them reduce the entry fee by integrating multiple deals and controlling the flow of goods and money. The other reduces the entry fee by incorporating a third-party agent into the exchange process. We examine the lower bound of the entry fee for both of these mechanisms and describe a calculation method by which this value can be obtained in linear time. Our results show that the described mechanism can effectively reduce the lower bound of the entry fee.     

M-TRAN: self-reconfigurable modular robotic system

In this paper, a novel robotic system called modular transformer (M-TRAN) is proposed. M-TRAN is a distributed, self-reconfigurable system composed of homogeneous robotic modules. The system can change its configuration by changing each module's position and connection. Each module is equipped with an onboard microprocessor, actuators, intermodule communication/power transmission devices and intermodule connection mechanisms. The special design of M-TRAN module realizes both reliable and quick self-reconfiguration and versatile robotic motion. For instance, M-TRAN is able to metamorphose into robotic configurations such as a legged machine and hereby generate coordinated walking motion without any human intervention. An actual system with ten modules was built and basic operations of self-reconfiguration and motion generation were examined through experiments. A series of software programs has also been developed to drive M-TRAN hardware, including a simulator of M-TRAN kinematics, a user interface to design appropriate configurations and motion sequences for given tasks, and an automatic motion planner for a regular cluster of M-TRAN modules. These software programs are integrated into the M-TRAN system supervised by a host computer. Several demonstrations have proven its capability as a self-reconfigurable robot.     

Mechanical properties of 0.40 pct C-Ni-Cr-Mo high strength steel having a mixed structure of martensite and bainite

A study has been systematically made of the effect of bainite on the mechanical properties of a commercial Japanese 0.40 pct C-Ni-Cr-Mo high strength steel (AISI 4340 type) having a mixed structure of martensite and bainite. Isothermal transformation of lower bainite at 593 K, which appeared in acicular form and partitioned prior austenite grains, in association with tempered marprovided provided a better combination of strength and fracture ductility, improving true notch tensile strength (TNTS) and fracture appearance transition temperature (FATT) in Charpy impact tests. This occurred regardless of the volume fraction of lower bainite present and/or the tempering conditions employed to create a difference in strength between the two phases. Upper bainite which was isothermally transformed at 673 K appeared as masses that filled prior austenite grains and had a very detrimental effect on the strength and fracture ductility of the steel. Significant damage occurred to TNTS and FATT, irrespective of the volume fraction of upper bainite present and/or the tempering conditions employed when the upper bainite was associated with tempered martensite. However, when the above two types of bainite appeared in the same size, shape, and distribution within tempered martensite approximately equalized to the strength of the bainite, a similar trend or a marked similarity was observed between the tensile properties of the mixed structures and the volume fraction of bainite. From the above results, it is assumed that the mechanical properties of high strength steels having a mixed structure of martensite and bainite are affected more strongly by the size, shape, and distribution of bainite within martensite than by the difference in strength between martensite and bainite or by the type of mixed bainite present. The remarkable effects of the size, shape, and distribution of bainite within martensite on the mechanical properties of the steel are briefly discussed in terms of the modified law of mixtures, metallographic examinations, and the analyses of stress-strain diagrams.     

Application of a proton-electron mechanism to the cathodic reduction of multilayer oxide on a platinum electrode in perchloric acid solution

The electrochemical reduction of the multilayer oxide on smooth Pt electrode in HClO₄ solution was studied using a galvanostatic technique. This oxide is completely reduced in the potential region where the electrosorption of hydrogen on Pt electrode occurs and the reduction rate depends on the hydrogen coverage. A previously proposed proton-electron mechanism was applied to the reduction of the multilayer oxide. The linear relationship between Q_Hs and log i/Q_Hs, which is expected from this mechanism, was confirmed in the coverage range of H_s from 0.1 to 1, where i is the reduction rate expressed with current density and Q_Hs the quantity of strongly-adsorbed hydrogen on the electrode surface of unit area.     

Robotic range sensor with projection of bright ring pattern

A new type of optical range sensor is being proposed as a robotic sensor. The range sensor consists of the projection subsystem of an axially symmetrical light sheet and the detection subsystem for monitoring the focussing process of a lens. The projection subsystem produces a bright ring pattern through an objective lens on the surface of an object. Next, the distance from the range sensor to the surface of an object is calculated from the position of the lens. The prototype range sensor is able to measure the distance in the range of 430 to 570 mm with an accuracy of 0.3 mm. As the position of the objective lens is controlled so that the ring pattern projected on the surface of an object becomes a fine spot, the detection subsystem finds the position of the objective lens on which the output of photodiode comes to be maximum.     

Rapid Formation of Zinc Oxide Films by an Atmospheric-Pressure Chemical Vapor Deposition Method

Zinc oxide films were prepared by an atmospheric-pressure chemical vapor deposition method using (acetylacetonato)-zinc as a source material. Transparent and uniform ZnO films of considerable area (20 × 70 mm, ∼0.3 μm thick) could be obtained easily on a crown glass (CGW #200) with a high deposition rate. The deposition rate first remained constant with increasing substrate temperature ( T _s), then increased abruptly from 120 nm/min at T _s= 550°C to 220 nm/min at T _s= 600°C, and finally stopped increasing above T _s= 600°C. The maximum preferred orientation and best crystallinity of the films were obtained at T _s= 550°C.     

Ray analysis of W-type slab optical waveguides with core distortions

The letter considers a W-type slab waveguide in which a number of modes propagate. The significant feature is found to be the mode reservoir effect of a ray temporarily transformed into a leaky ray, owing to imperfections of the guide. Such disturbances cause little radiation loss if they are localised within the attenuation length of the leaky ray.