Tricycle-style operation interface for children to control a telepresence robot

Telepresence robots will provide significant value to childhood education. They will offer children opportunities to join remote classrooms and to communicate with speakers of different languages in more enriched ways than are available by conventional video conferencing. However, the introduction of child-operated telepresence robots has yet to be tested. The design of the operation interface presents a particular challenge. In this study, we report the development of a tricycle-style operation interface based on requirements identified through classroom field observations. It was designed for intuitive use, even by young children, without the need of detailed instruction. The usability of the interface was tested in a field experiment involving 20 participants (4–8 years old). The participants were asked to perform six elementary tasks using a telepresence robot system controlled either by the tricycle-style interface or a standard video-game controller. The operational performance of the tricycle-style interface was found to be superior to that of the standard controller. The advantages and disadvantages of both interfaces are discussed.     

Observations on non-silent self-stabilizing algorithms in sensor networks with probabilistically intermittent link failures

A wireless sensor network is a set of nodes, each is equipped with a sensing device and a wireless communication device. Because centralized control is hard to achieve in a large scale sensor network, self-∗ is a key concept in the design of a wireless sensor network. Self-stabilization is one of the self-∗ properties, and it is one of the most promising theoretical backgrounds for self-organizing wireless sensor network protocols. Herman [T. Herman, Models of self-stabilization and sensor networks, in: Proceedings of the 5th International Workshop of Distributed Computing, IWDC, 2003, pp. 205-214] proposed Cached Sensornet Transform (CST for short) for design and implementation of self-stabilizing algorithms for sensor networks. It transforms a self-stabilizing algorithm in a high-level computational model to a program for sensor networks. Our contribution in this paper is threefold. We show that there exists a non-silent algorithm that behaves correctly in a high-level computational model but its transformed version by CST does not behave correctly if packets are lost. We show a sufficient condition for original algorithms and networks such that the algorithm transformed by CST behaves correctly. As a case study, we present a token circulation algorithm that behaves correctly by CST and derive the upper bound of its expected convergence time.     

Development of Low Temperature SQUID Gradiometer Array for Metallic Magnetic Microcalorimeters

We report on the performance of two types of SQUID gradiometers developed for the readout of magnetic calorimeters. Our previously developed low dissipation SQUID gradiometer optimized for low temperature operation has demonstrated the flux noise level of under a magnetic field of 2.5 mT and 150 mK. With a cylindrical Au:Er paramagnetic sensor mounted inside the octagonal pickup washer of the SQUID gradiometer, we succeeded in detecting X-ray signals. However, our achieved energy resolution was 47.2±2.1 eV at 5.9 keV limited by the high operating temperature of 150 mK and by a magnetic field, small for that temperature, due to the limited critical current of the field coils. Based on these results, we fabricated new arrays of SQUID gradiometer by tuning the line width and the number of turns of the field coils and shunt resistance to realize a lower noise level and a larger magnetic field. Furthermore, arrays of SQUID gradiometer with meander patterned pickup washer was fabricated which provides a stronger coupling between the paramagnetic sensor and the pickup washer, and a larger magnetic field at the sensor.      

Supervisory Control of a Class of Concurrent Discrete Event Systems Under Partial Observation

In this paper, we study supervisory control of a class of discrete event systems with simultaneous event occurrences, which we call concurrent discrete event systems, under partial observation. The behavior of the system is described by a language over the simultaneous event set. First, we prove that L_m(G)-closure, controllability, observability, and concurrent well-posedness of a specification language are necessary and sufficient conditions for the existence of a nonblocking supervisor. Next, we synthesize a supervisor that achieves the infimal closed, controllable, observable, and concurrently well-posed superlanguage of a specification language. Finally, we synthesize a supervisor that achieves a maximal closed, controllable, observable, and concurrently well-posed sublanguage of a closed specification language.     

Structural investigation on column-chromatographed vacuum residues of various petroleum crudes by 13C nuclear magnetic resonance spectroscopy

Proton and carbon-13 nuclear magnetic resonance spectroscopy of various vacuum residues and their fractionated samples were carried out to investigate average molecular structures. The structural parameters derived from carbon distribution agreed with those derived from p.m.r. within experimental error. In the aliphatic region of the c.m.r. spectra, characteristic peaks assignable to $\text{(CH}{}_2\text{)}{}_{\mathrm{n}}\text{? n ≧ 6 (29.7}\text{ppm}\text{)}$ and CH₃CH₂CH₂CH₂ (14.1 ppm) etc. can be observed. The relative intensities of these peaks suggest that the methylene chain contained in vacuum residues is much longer ($\text{(CH}{}_2\text{)}{}_{\mathrm{n}}\text{? n ≧ 12}$) than has been considered previously. Using the information about the aliphatic region of the c.m.r. spectrum and the structural parameters, an average structural model was deduced.     

Adaptive timeliness of consensus in presence of crash and timing faults

The Δ$\mathrm{\Delta }$-timed uniform consensus is a stronger variant of the traditional consensus and it satisfies the following additional property: every correct process terminates its execution within a constant time Δ$\mathrm{\Delta }$ (Δ$\mathrm{\Delta }$-timeliness), and no two processes decide differently (uniformity). In this paper, we consider the Δ$\mathrm{\Delta }$-timed uniform consensus problem in presence of _fc$f_{\mathrm{c}}$ crash processes and _ft$f_{\mathrm{t}}$ timing-faulty processes, and propose a Δ$\mathrm{\Delta }$-timed uniform consensus algorithm. The proposed algorithm is adaptive in the following sense: it solves the Δ$\mathrm{\Delta }$-timed uniform consensus when at least _ft+1$f_{\mathrm{t}}+1$ correct processes exist in the system. If the system has less than _ft+1$f_{\mathrm{t}}+1$ correct processes, the algorithm cannot solve the Δ$\mathrm{\Delta }$-timed uniform consensus. However, as long as _ft+1$f_{\mathrm{t}}+1$ processes are non-crashed, the algorithm solves (non-timed) uniform consensus. We also investigate the maximum number of faulty processes that can be tolerated. We show that any Δ$\mathrm{\Delta }$-timed uniform consensus algorithm tolerating up to _ft$f_{\mathrm{t}}$ timing-faulty processes requires that the system has at least _ft+1$f_{\mathrm{t}}+1$ correct processes. This impossibility result implies that the proposed algorithm attains the maximum resilience about the number of faulty processes. We also show that any Δ$\mathrm{\Delta }$-timed uniform consensus algorithm tolerating up to _ft$f_{\mathrm{t}}$ timing-faulty processes cannot solve the (non-timed) uniform consensus when the system has less than _ft+1$f_{\mathrm{t}}+1$ non-crashed processes. This impossibility result implies that our algorithm attains the maximum adaptiveness.     

Two-stage pyrolysis of heavy oils. 1. Pyrolysis of vacuum residues for olefin production in a batch-type reactor

Two-stage pyrolysis of Iranian heavy and Taching vacuum residues using a batch-type reactor has been carried out to produce lower olefins. The reactor tube was constructed with two zones in which temperatures were controlled at ≈ 440 °C and 700–800 °C. Vacuum residues (mw 900–1000) were pyrolysed into cracked oils (mw 300–400) in the first, low-temperature, stage, which were carried to the second, high-temperature, stage by an argon flow to undergo subsequent pyrolysis. In comparison with the vacuum residues pyrolysed directly at high temperature, the ethylene yield increased by a factor of 1.5–1.8 using the two-stage procedure. 26% of ethylene was obtained from the Taching vacuum residue and 15% from the Iranian Heavy residue. Pyrolysis residues can be recovered without carbonization under the conditions of the first stage.     

Contouring of polished single-crystal silicon plates by wire electrical discharge machining

We investigate the effect of cutting by wire electrical discharge machining (WEDM) on the shape accuracy of polished single-crystal silicon. Single-crystal silicon plates are polished, and then contoured in deionized water or in oil by WEDM. The shape accuracy of the polished surfaces is measured with an interferometer. As a result, the polished surfaces are deformed into convex shapes by WEDM cutting. The polished surfaces tend to become flat as the roughness of the cut sections decreases, and the flatness is independent of the type of cutting liquid. Cutting in oil is advantageous for maintaining the smoothness of polished surfaces. These findings confirm that, in the contouring process of polished single-crystal silicon blocks, smooth and high-accuracy surfaces are achieved by conducting rough- and finish-cutting WEDM processes in oil.     

Evaluation of the ACR-NEMA standard for communications in digital radiology

An implementation and evaluation of a prototype multivendor communications system which complies with the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) standard for communications in digital radiology is discussed. The system allows communications between interfaces from different manufacturers within a networked environment. The implementation includes network software compatible with the International Standards Organization's Open Systems Interconnect standard. The experience of the implementation effort and the evaluation of the system provide the basis for a critique of the ACR-NEMA standard. It is concluded that the ACR-NEMA standard is not well suited for application to the networked environment of picture archiving and communications systems. Two possible solutions are recommended for this problem. The first is a major revision of the existing standard. The second is the development of a family of network communications standards for digital radiology.