Japan's sewerage system

This paper traces the history of sewer construction in Japan. The first sewers were built for flood control, and as late as the end of the Second World War there were only six cities enjoying sewer systems with treatment facilities. Rapid industrialization increased pollution problems and led to accelerated sewer development. Advances in the technology of sewage treatment are outlined. Today 30% of Japan's population is served by sewer systems, and identifying cost‐effective means of increasing that proportion is a major priority. The Experimental Sewer System, developed in Tokyo, is described. Finally, a new method for the estimation of peak flow in sewer pipes, entitled grid analysis, is presented.     

High-Speed Packet Switching Systems for Multimedia Communications

High-speed packet switching (HPS) systems can Provide flexible, economical, high-quaiity services for integrated voice, video, and data communications. To realize such HPS systems, methods have been developed to bring about high-speed protocol processing as well as a system architecture for facilitating high-throughput switching. Adopting the parallel processing algorithm into protocol processing allows us to achieve high-speed packet protocol processing of about 100 times faster than conventional processing. Furthermore, a fully distributed system architecture in addition to hierarchical interconnection networks can achieve high-capacity packet switching systems. The proposed HPS system is thus capable of accommodating lines of up to 10-50 Mbits/s, of providing high-throughput switching capability of 1 000 000 packets/s, and of having an average delay of less than 2 ms. Furthermore, an evaluation of network delay performances of video conferencing and voice communications indicate that HPS systems are quite suitable for handling such multimedia communications.     

Infrared Detection by Si-Ti-C-O Fibers

Electrical resistivity at 20° to 90°C and infrared (IR) responses (thermal time constant and responsivity of electrical resistance changes) were measured on Si-Ti-C-O fibers. The fibers showed negative temperature coefficient resistance-temperature characteristics, and the thermistor constant B was 890 to 4760 K. A fast and steady output (resistance change) was observed in response to IR radiation from a 600 K blackbody furnace. The IR response was affected markedly by detector structure; the thermal time constant decreased with decreasing length of the fibers, and the responsivity increased with decreasing number of the fibers. In an IR detector with a separate arrangement of a few ( n =10) fibers with a short length (1 mm) and a low resistivity (80 Ω·cm), a thermal time constant of 3.5 ms and a responsivity of 63 V/W were obtained. A fast and steady IR response of Si-Ti-C-O fibers suggests the possibility of detecting both stationary and moving IR sources.     

Surface-grafted triruthenium ketenylidene clusters and their catalytic activity in co exchange and hydroformylation of ethylene

A triruthenium ketenylidene cluster [PPN]₂[Ru₃(CO)₉(CCO)] was deposited on MgO, SiO₂, and SiO₂-Al₂O₃, and the nature of surface species on the oxides were studied by an IR spectroscopic study along with catalytic performances in¹³CO exchange reaction and hydroformylation of ethylene. The IR study suggested the stoichiometric protonation of [Ru₃(CO)₉(CCO)]^2-with surface hydroxyl groups on SiO₂ and SiO₂-Al₂O₃ to give [HRu₃(CO)₉(CCO)]^– and H₂Ru₃(CO)₉(CCO), respectively. H₂Ru₃(CO)₉(CCO)/SiO_2– Al₂O₃ was active for¹³CO exchange reaction, while [Ru₃(CO)₉(CCO)]^2–/MgO showed high activity and selectivity toward propanol in hydroformylation of ethylene.     

Comprehensive treatment of advanced neuroblastoma involving autologous bone marrow transplant

Encouraging results are reported with high-dose chemotherapy and total body irradiation followed by autologous bone marrow transplantation in the treatment of advanced neuroblastoma. However, relapse remains a significant problem. We used high-dose chemotherapy, surgery, intraoperative radiation and an autologous bone marrow transplant treated in vitro to remove tumor cells followed by 13-cis-retinoic acid to treat 36 children with advanced neuroblastoma. This comprehensive treatment appears to improve the survival rate of patients with advanced neuroblastoma, including those with N-myc amplification and bony involvement. The disease-free survival rate was 66% (95% confidence interval, 49-84%) at 3 years. All patients who received 13-cis-retinoic acid developed cheilitis, but no bone marrow depression occurred in these patients. Five patients developed hemolytic uremic syndrome (HUS) post-transplant. This may have been related to the procedure used for total body irradiation. Patients who had their kidneys shielded during this procedure did not develop this syndrome. Patients who received local irradiation at the primary site showed no evidence of relapse in this region, indicating that such therapy may help to prevent a relapse. These data suggest a high rate of 3 year disease-free survival with this treatment strategy. The nonrandomized nature of the study and use of multiple modalities precludes analysis of the specific contribution of each.     

Neural network application for direct feedback controllers

The author presents a learning algorithm and capabilities of perceptron-like neural networks whose outputs and inputs are directly connected to plants just like ordinary feedback controllers. This simple configuration includes the difficulty of teaching the network. In addition, it is preferable to let the network learn so that a global and arbitrary evaluation of the total responses of the plant will be optimized eventually. In order to satisfy these needs, genetic algorithms are modified to accommodate the network learning procedure. This procedure is a kind of simulated evolution process in which a group of networks gradually improves as a whole, by crossing over connection weights among them, or by mutational changes of the weights, according to fitness values assigned to each network by a global evaluation. Simulations demonstrate that these networks can be optimized in terms of various evaluations, and they can discover schemes by themselves, such as state estimation and nonlinear control.     

Molecular dynamics and multiscale homogenization analysis of seepage/diffusion problem in bentonite clay

A scheme combining a molecular behaviour and macro‐continuum phenomenon is presented for bentonite clay, which is a key component of a barrier system for disposal and containment of hazardous wastes. On designing a disposal facility we use a macro‐phenomenological model. However the existing model is not sufficiently effective. Bentonite is a microinhomogeneous material. Properties of the saturated bentonite are characterized by montmorillonite and water, called montmorillonite hydrate. Since the crystalline structure of montmorillonite determines the fundamental properties of the montmorillonite hydrate, we analyse its molecular behaviour by applying a molecular dynamics simulation to enquire into the physicochemical properties of the montmorillonite hydrate such as diffusivity of chemical species. For extending the microscopic characteristics of constituent materials to a macroscopic diffusion behaviour of the microinhomogeneous material we apply a multiscale homogenization analysis, especially in order to treat micro‐level of adsorption behaviour. Copyright © 2002 John Wiley & Sons, Ltd.