Abstract: A network node of a local area wireless network preferentially tries to connect with a first node having the primary connection relationship with the network node in a first connection time window; when the network node fails to connect with the first node under a predetermined condition, the network node tries to connect with a second node having the backup connection relationship with the network node in a second connection time window. After the network node is connected with and finishes communicating with the first or second node, the network node enters into standby or dormancy state and tries to establish connection in a subsequent first connection time window or a second connection time window. By using priority or backup routing method and setting connection time window, the power consumption management and networking management mechanism of each node of the network are simplified. Each network node can operate at a low power consumption level.

Abstract: The present invention discloses methods and systems for detecting the health status of a bolt which fastens a rotor blade of a wind turbine. Values of the axial stress/strain of the bolt and motion and orientation data are acquired in different aerial orientations. Values of the prestress/strain and load-stress/strain are obtained using the values of the axial stress/strain and the motion and orientation data. Values of the prestress/strain and load-stress/strain are compared with the reference values. The health status of the bolt, rotor blade, and the wind turbine system is determined based on the comparison results. The method is noninvasive and doesn't affect the function and performance of the bolt and the turbine system.

Abstract: The present invention discloses methods and systems for detecting the tightness state of a bolt or nut under inspection. At least one sensor is mounted on the bolt or nut. At least another sensor is mounted on a structure where the bolt or nut is mounted. Data of motion and/or orientation is acquired. A first angle of the bolt or nut in a plane of rotation of the bolt or nut is calculated. The first angle is related to rotation of the bolt or nut. A second angle of the structure in the plane of rotation of the bolt or nut is calculated. The second angle is unrelated to rotation of the bolt or nut. The initial angle difference between the first and second angles is calculated when the bolt or nut is tight. A subsequent angle difference between the first and second angles is calculated during the inspection. Using the initial angle difference and the subsequent angle difference, the screwed-out angle of the bolt or nut is obtained.

Abstract: The present invention discloses a method and system for detecting the fastening state of a fastening structure which fixes structural elements. At least a first vibration sensor is mounted on a first structural element for collecting vibration data of the first structural element. At least a second vibration sensor is mounted on a second structural element or on the fastening structure for collecting vibration data of the second structural element or the fastening structure. The fastening state of the fastening structure is determined using the vibration data collected. The method and system enable detection of the fastening state of a fastening structure with low-power consumption and low cost.

Abstract: The present invention discloses ultrasonic nondestructive methods for pipe wall thickness measurement at high or low temperatures. An ultrasonic detection device comprises a first and a second ultrasonic waveguide. The waveguide length is selected according to the surface temperature of a pipe under inspection. A first piezoelectric plate causes generation of a plurality of ultrasonic excitation signals which is transmitted to the pipe through the first ultrasonic waveguide. The plurality of ultrasonic excitation signals has different group speeds when traveling along the first ultrasonic waveguide. The reflected ultrasonic wave signals are collected and transmitted to a second piezoelectric plate by the second ultrasonic waveguide. The pipe wall thickness is calculated using an ultrasonic wave signal which has the highest group speed. The first and second waveguides are arranged parallel and side by side.