The eta phases and mechanical properties of TIG welded joints of WC-Co cemented carbide and steel

The tungsten-inert-gas (TIG) arc welding experiments of cemented carbide YG30 and steel 45 were carried out using the Ni-Fe-C filling alloys. The eta phases and mechanical properties of welded joints were analyzed by means of scanning electronic microscope (SEM) , transmission electronic microscope (TEM) coupled with selected diffraction, electronic probe microanalysis and bending strength method. The experimental results show that the chemical composition of the filling alloys affects eta phase formation. When the carbon and nickel contents in filling alloys are O. 61 wt% and 55. 29 wt% ,respectively, no eta phases form. And the joint bending strength is the highest to 1. 352 GPa. But if they are O. 01wt% and 55.38wt%, the eta phases are formed at the boundaries of the cemented carbide and the weld, and the thickness of eta phase layer is about 110 micrometers. And the joint bending strength is low. Usually, these eta phases are anomalously granular,and easy to accumulate at the boundaries between cemented carbides and the weld. They are multiple M6C rich in tungsten and iron.     

control with limited communication and message losses

We propose an H^∞ approach to a remote control problem where the communication is constrained due to the use of a shared channel. The controller employs a periodic time sequencing scheme for message transmissions from multiple sensors and to multiple actuators of the system. It further takes into account the information on the random message losses that occur in the channel. An exact characterization for controller synthesis is obtained and is stated in terms of linear matrix inequalities. Furthermore, an analysis on the loss probabilities of the messages to accomplish stabilization is carried out. The results are illustrated through a numerical example.     

Microstructure and properties of (Sr, Ca)CuO2/(Sr, Ca)RuO3 multilayers

Epitaxial multilayer thin films of infinite-layer (Sr, Ca)CuO₂ and perovskite (Sr, Ca)RuO₃ have been prepared on (100) SrTiO₃ substrates by multitarget rf magnetron sputtering. X-ray diffraction analyses revealed that the multilayer structure of (Sr, Ca)CuO₃/(Sr, Ca)RuO₃ was successfully fabricated with a minimum layer thickness of 20 Å. Transmission electron microscopy measurements of the multilayers indicated that there was no dislocation which normally exists in single-layer films with an infinite-layer structure. Resistivities of multilayer films at room temperature ranged from 1 to 10 m cm and showed semiconductor-like dependence against the temperature.     

Spherical gradient-index polymer lens with low spherical aberration

A sphere lens with a spherical gradient index (GRIN) was prepared by the modified suspension polymerization technique. GRIN spheres with quadratic- and linear-index distributions were obtained by two different methods to confirm the effect of the GRIN profile on the focusing property of the sphere lens. It was confirmed in both theory and experiment that the spherical aberration of such GRIN spheres was remarkably decreased compared with that of a homogeneous sphere.     

Thermodynamics of oxygen,nitrogen and sulfur in liquid iron equilibrated with CaO-TiOx and CaO-Al2O3-TiOx melts

Equilibria between CaO-TiO_x or CaO-Al₂O₃-TiO_x melts and liquid iron with respect to O, N and S were studied at 1873 K as a function of Ti (or Al) content in metal, using a CaO or an Al₂O₃ crucible. The Al-O and Ti-O relations in liquid iron were studied, and nitride and sulfide capacities defined by and , respectively, were obtained from nitrogen and sulfur distribution ratios, coupled with the analyzed oxygen content in liquid iron or the P_O2 determined by Ti/TiO₂ equilibrium. Based on these results, activities of Al₂O₃ and activity coefficients of TiO₂ and TiO_1.5 were evaluated.     

Event-triggered control for discrete-time multi-agent average consensus

We consider the average consensus problem for the multi-agent system in the discrete-time domain. Three triggering based control protocols are developed, which dictate the broadcast and control update instants of individual agents to alleviate communication and computational burden. Lyapunov-based design methods prescribe when agents should communicate and update their control so that the network converges to the average of agents' initial states. We start with a static version of the distributed event-triggering law and then generalize it so that it involves an internal auxiliary variable to regulate the threshold dynamically for each agent. The third protocol uses a self-triggering algorithm to avoid continuous listening wherein each agent estimates its next triggering time and broadcasts it to its neighbors at the current triggering time. Numerical simulations are shown to validate the efficacy of the proposed algorithms.     

Measurement of aluminum or silicon activity in Fe-Ni (< 30 %) alloys using mullite and ZrO2-based solid electrolyte galvanic cell

Using mullite (3Al₂O₃·2SiO₂)-tube type and ZrO₂ (MgO mole fractions of 9 %)-plug type solid electrolyte, the activities of Al in the Fe-15, 29% Ni-0.002 to 0.84% Al (mass contents in%) alloys were measured at 1873 K in an Al₂O₃ crucible, and those of Si in the Fe-13, 28% Ni-0.13 to 2.3% Si alloys were measured at 1823 K in a mullite crucible with an excess of SiO₂. The interaction coefficients of and were determined as ?0.0173 ± 0.0052 and 0.00021 ± 0.00007, respectively, and those of and were determined as 0.0094 ± 0.0049 and ?0.00008 ± 0.00004, respectively. The oxygen activities obtained by the EMF measurements were compared with those obtained from the contents of analyzed oxygen. The oxygen activities in the Fe-Ni-Al alloys were found to be supersaturated. The interaction coefficients of and were determined as 0.0027 ± 0.0012 and 0.00012 ± 0.00004, respectively, from the contents of analyzed oxygen in Fe-Ni-Si alloys.     

Cooperation of categorical and behavioral learning in a practical solution to the abstraction problem

Real robots should be able to adapt autonomously to various environments in order to go on executing their tasks without breaking down. They achieve this by learning how to abstract only useful information from a huge amount of information in the environment while executing their tasks. This paper proposes a new architecture which performs categorical learning and behavioral learning in parallel with task execution. We call the architectureSituation Transition Network System (STNS). In categorical learning, it makes a flexible state representation and modifies it according to the results of behaviors. Behavioral learning is reinforcement learning on the state representation. Simulation results have shown that this architecture is able to learn efficiently and adapt to unexpected changes of the environment autonomously. Atsushi Ueno, Ph.D.: He is a research associate in the Artificial Intelligence Laboratory at the Graduate School of Information Science at the Nara Institute of Science and Technology (NAIST). He received the B.E., the M.E., and the Ph.D. degrees in aeronautics and astronautics from the University of Tokyo in 1991, 1993, and 1997 respectively. His research interest is robot learning and autonomous systems. He is a member of Japan Association for Artificial Intelligence (JSAI). Hideaki Takeda, Ph.D.: He is an associate professor in the Artificial Intelligence Laboratory at the Graduate School of Information Science at the Nara Institute of Science and Technology (NAIST). He received his Ph.D. in precision machinery engineering from the University of Tokyo in 1991. He has conducted research on a theory of intelligent computer-aided design systems, in particular experimental study and logical formalization of engineering design. He is also interested in multiagent architectures and ontologies for knowledge base systems.