## 3 Research Method
### Experimental Test
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Radio Telescope** & **Reflector Diameter (m)** & **Measured Component** & **Number of Sensors** \\ \hline BIMA [79] & 6 & BUS & 32 \\ ASTE [130] & 10 & BUS, Pedestal, Fork & 170 \\ OVRO [79] & 10.4 & BUS & 48 \\ VertexRSI-ALMA [127] & 12 & Pedestal, Fork, BUS & 89 \\ AEC-ALMA [127] & 12 & Pedestal, Fork & 101 \\ ALMA-J [131] & 12 & BUS & 227 \\ FCRAO [132] & 14 & BUS, Quadripod, Subreflector & 30 \\ JCMT [79] & 15 & BUS, Alidade & 220 \\ IRAM [129] & 30 & Yoke, BUS, Quadripod & 156 \\ NRO [88;89] & 45 & BUS & 140 \\ RT-70 [133] & 70 & BUS & 200 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Some cases of temperature field tests for radio telescopes. Figure 5: Embedded temperature sensors in the cable (cross-section view) [60;61]. The test contents when testing temperature effect include stress, displacement, cable force, etc. ; stress can be measured by strain gauges [27] or vibrating wire sensors [30], displacement can be obtained using displacement transducers [60], GPS receivers [61] or 3D laser scanning [32], and cable force can be directly monitored by tension sensors [23] or calculated from displacement [63]. Generally, the measured temperature effect is used to analyze its relationship with the measured temperature, so the measurement point layout of the temperature effect is roughly consistent with that of temperature in many cases. [PERSON] used 268 vibrating wire sensors, which integrate the test functions of stress and temperature, to measure the temperature and stress of the Beijing National Stadium's space truss structure in order to directly study the correlation between temperature field and stress, and the test results showed that the variation of temperature field was an important factor leading to high stress [30]. To study the relationship between the temperature field and the deflection of the steel box girder in the Zhijiang Cable-Stayed Bridge, 14 temperature sensors and 18 deflection sensors were arranged along the longitudinal direction of the bridge, with the longitudinal positions of T1-T14 and D3-D16 being the same [134]; the specific positions of these temperature and deflection sensors are shown in Figure 7. Based on comparative analysis of the test data, it was shown that the time-variance laws of girder temperature and girder deflection were similar, and there was a basically linear relationship between the temperature field and the deflection of the box girder at night, indicating that the girder deflection was greatly affected by the girder temperature. This method of determining the layout of measuring points to measure temperature effect was also applied in the studies of [PERSON] [25], [PERSON] [27], [PERSON] [45], etc. In addition, measuring points are also arranged specifically at locations with significant temperature effects. Figure 8 shows the distribution of temperature sensors, strain gauges, GPS receivers and displacement transducers for the Tsing Ma Bridge [61]. From the figure, it can be seen that there are many differences in the arrangement of measuring points of temperature and temperature effect; the installed temperature sensors are concentrated in four areas for monitoring cable temperature and deck temperature, while the arrangement of temperature effect measuring points is much more intensive. The displacement measuring points (GPS receiver and displacement transducer) are not only arranged along the longitudinal direction to measure the overall displacement variation of the bridge, they are also placed in the bridge tower and main cable to monitor their movement, and the 110 strain gauges were installed in three deck sections to monitor for potentially large strain. Figure 6: Temperature measuring points layout of two radio telescope [127,129]. (**a**) VertexRSI 12-m prototype telescope. (**b**) IRAM 30-m Telescope.