Abstract: An apparatus for determining a road pavement surface condition over a wide area has a road noise sensor (12). A temporal frequency analyzer (18) converts a road noise signal from the road noise sensor (12) to a temporal frequency signal. A processing circuit (20) receives the temporal frequency signal from the temporal frequency analyzer (18) and analyzes the temporal frequency signal to determine the road pavement surface condition.

Abstract: An electronic nervous system (10) for a roadway (12), has a plurality of nodes (14). The plurality of nodes (14) parallel the roadway and are connected by an information link (20). A plurality of sensors (16) are coupled to the plurality of nodes (14) and the output of the sensors (16) are processed by the nodes to form symbolic patterns (18). The symbolic patterns (20) travel along the information link (20). By comparing symbolic patterns (18) the state of the roadway (12) can be determined. The state can include a metric that measures how well traffic is flowing as well as determines transit times between nodes. A plurality of traffic signals (34) are coupled to the nodes (14) and are adjusted based on the symbolic patterns (18). A subset of the plurality of nodes (14) are coupled to a node supervisor (36).

Abstract: In-situ Si.sub.3 N.sub.4 whisker growth mechanisms have enhanced the microstructure of ceramic materials such as SiC through controlled growth of elongated beta-type Silicon Nitride grains. During liquid phase sintering at temperatures not exceeding 1850.degree. C., alpha-type Silicon Nitride dissolves into the liquid phase and reprecipitates as an elongated or acicular beta modification. The Si.sub.3 N.sub.4 reinforced microstructures can be formed by the controlled recrystallization of beta-type Silicon Nitride. In-situ whisker growth is enhanced or optimized through the use of thermal treatments and/or additions of seed materials. Finely divided beta-type Silicon Nitride particles which are insoluble in the liquid phase during sintering, and therefore have been used to provide nucleation sites for whisker growth are employed. Thermal treatments have been designed to promote directional growth (elongation) as opposed to development of less elongated type grains.

Abstract: In-situ Si.sub.3 N.sub.4 whisker growth mechanisms have enhanced the microstructure of ceramic materials such as SiC through controlled growth of elongated beta-type Silicon Nitride grains. During liquid phase sintering at temperatures not exceeding 1850.degree. C., alpha-type Silicon Nitride dissolves into the liquid phase and reprecipitates as an elongated or acicular beta modification. The Si.sub.3 N.sub.4 reinforced microstructures can be formed by the controlled recrystallization of beta-type Silicon Nitride. In-situ whisker growth is enhanced or optimized through the use of thermal treatments and/or additions of seed materials. Finely divided beta-type Silicon Nitride particles which are insoluble in the liquid phase during sintering, and therefore have been used to provide nucleation sites for whisker growth are employed. Thermal treatments have been designed to promote directional growth (elongation) as opposed to development of less elongated type grains.