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According to the special working conditions of Chinese railway system, the failure prediction and health management system for the bearing of running gear of rolling stock is established, which includes data collection, storage and analysis. The overall structure of the system and the functions of each part in the system are introduced in detail, and the development of failure prediction and health management system for Chinese railway is prospected. After the initial trial of the system, on the basis of ensuring the safe operation of the rolling stock, the downtime caused by bearing failure or overhaul can be effectively reduced, the service efficiency of the rolling stock is improved, and data and technical support are provided for optimizing the design, manufacturing and assembly technology improvement of the bearing.

Sea levels are rising around the world, and this is a particular concern along most of the coasts of the United States. A 1989 EPA report shows that sea levels rose 5-6 inches more than the global average along the Mid-Atlantic and Gulf Coasts in the last century. The main reason for this is coastal land subsidence. This sea level rise is considered more as relative sea level rise than global sea level rise. Thus, instead of studying sea level rise globally, this paper describes a statistical approach by using factor analysis of regional sea level rates of change. Unlike physical models and semi-empirical models that attempt to approach how much and how fast sea levels are changing, this methodology allows for a discussion of the factor(s) that statistically affects sea level rates of change, and seeks patterns to explain spatial correlations. Los niveles del mar crecen alrededor del mundo, y este es un problema que afecta a la mayoría de las costas en los Estados Unidos. Un reporte de 1989 de la Agencia de Protección Ambiental de los Estados Unidos (EPA, por sus siglas en inglés) muestra que el nivel del mar creció de 5 a 6 pulgadas más que el promedio global en el Atlántico Medio y la costa del Golfo en el siglo pasado. La principal razón para esto es el hundimiento de la tierra costera. Este crecimiento del nivel del mar es considerado más como uno relativo antes que global. Así, en lugar de estudiar el crecimiento global del nivel del mar, este artículo describe un enfoque estadístico usando análisis factorial del cambio en las razones del nivel del mar regional. Contrario a los modelos físicos o semiempíricos, que tratan de aproximar qué tanto y qué tan rápido cambian los niveles del mar, esta metodología permite una discusión de los factores que afectan estadísticamente las razones de cambio del nivel del mar, y busca patrones que expliquen correlaciones espaciales.

We investigate the characteristic features of data transmission in sensor networks. According to these features, a three-layer model appropriate for sensor networks was obtained by simplifying the OSI seven-layer model. Using this simplified model, a high-speed reliable transmission protocol was presented. Transmission efficiency is improved by optimizing the hardware-driver and simplifying the API functions and reliable transmission is realized through the serial number and request-response mechanism. This protocol provides higher transmission efficiency under the precondition of transmission reliability comparing with TCP/IP protocol. Our experiments showed that the optimized protocol has greatly improved the network utilization than TCP/IP and achieved a reliable transfer speed up to 920Mbps.

This paper presents a design of a FPGA-based 7-order 1-bit sigma-delta modulator with zero points residing in noise band. The modulator, incorporating with a 24-bit sine wave source, a 1-bit DAC and a subsequent reconstruction filter, generates a signal to test a high-precision sigma-delta ADC. The test signal, which contains both sine wave and high frequency noise, is sampled by the ADC under test. Usually, the noise in the test signal can not be fully suppressed by subsequent decimation filters of the ADC. So decimation filters should be taken into account for designing the modulator. To compensate for the noise suppression limitation of the decimation filters, zero points are introduced to the noise band of the modulator noise transfer function (NTF). With the adding of these noise band zero points, the SNR of ADC output data reaches 115dB in the range of 0~500Hz, which is about 10dB higher than that of a system without these zero points.