The self-propagating high-temperature syn-thesis method was used to synthesize the TiAl intermetallic compound, and two kinds of synthesis modes were studied in this paper. The results show that the thermal explosion ...The self-propagating high-temperature syn-thesis method was used to synthesize the TiAl intermetallic compound, and two kinds of synthesis modes were studied in this paper. The results show that the thermal explosion mode is suitable for the synthesis of TiAl ,the pre-heating tempera-ture has a great influence on the synthesis. Microstructure study show that the density of the sample fabricated by ther-mal explosion mode is higher than that fabricated by propa-gating mode.展开更多
In this work we present a novel approach for describing radio signal spaces for localization algorithms. We first introduce a new metric, the Discretely Distributed Log-H61der Metric （DDLHM）. The DDLHM is designed t...In this work we present a novel approach for describing radio signal spaces for localization algorithms. We first introduce a new metric, the Discretely Distributed Log-H61der Metric （DDLHM）. The DDLHM is designed to characterize the type and degree of signal distortion relative to Iognormal signal-to-distance path models. We first show how the DDLHM can describe and discriminate distortions in an exhaustive set of synthetic signal spaces. We then determine a reduced set of maximally diagnostic distortion parameters. Using only 4% of the maximal set of DDLHMs, we found the reduced set matches with an acceptable degree of error 95% of the time. Using the synthetic reduced set, we characterized a variety of wireless localization algorithms＇ behaviors to attenuation, bias, and multipath. We found algorithms made much different tradeoffs between best case and average case error. We then use the DDLHM to identify distortion types in three different physical environments using measured 802.11 signal strengths, and predict the positioning performance of several localization algorithms. Our approach predicts average localization error to within 2 meters of the observed average error.展开更多
文摘The self-propagating high-temperature syn-thesis method was used to synthesize the TiAl intermetallic compound, and two kinds of synthesis modes were studied in this paper. The results show that the thermal explosion mode is suitable for the synthesis of TiAl ,the pre-heating tempera-ture has a great influence on the synthesis. Microstructure study show that the density of the sample fabricated by ther-mal explosion mode is higher than that fabricated by propa-gating mode.
文摘In this work we present a novel approach for describing radio signal spaces for localization algorithms. We first introduce a new metric, the Discretely Distributed Log-H61der Metric （DDLHM）. The DDLHM is designed to characterize the type and degree of signal distortion relative to Iognormal signal-to-distance path models. We first show how the DDLHM can describe and discriminate distortions in an exhaustive set of synthetic signal spaces. We then determine a reduced set of maximally diagnostic distortion parameters. Using only 4% of the maximal set of DDLHMs, we found the reduced set matches with an acceptable degree of error 95% of the time. Using the synthetic reduced set, we characterized a variety of wireless localization algorithms＇ behaviors to attenuation, bias, and multipath. We found algorithms made much different tradeoffs between best case and average case error. We then use the DDLHM to identify distortion types in three different physical environments using measured 802.11 signal strengths, and predict the positioning performance of several localization algorithms. Our approach predicts average localization error to within 2 meters of the observed average error.
