Utilizing Moving Vehicles as Sensors for Bridge Condition Screening – A Laboratory Verification

Health condition monitoring of bridge structures is attracting considerable attention, conventionally relying on visual inspection, and measurement-based methods that involve sensors installed directly on bridges. In recent years, drive-by monitoring methods that treat moving vehicles as moving sensors have been proposed as alternatives; these methods aim to be lowcost, mobile, and target fast bridge condition screening. In this study, we address the current lack of sufficient experimental verification of such methods. Laboratory experiments were conducted using a test vehicle system equipped with accelerometers in order to verify the practical feasibility of three drive-by methods: (1) bridge-frequency extraction using the Fourier spectrum of a vehicle’s dynamic response, (2) damage detection using the change in a vehicle’s spectral distribution pattern, and (3) roadway surface profile identification

Structural Health Monitoring of Bridges Using Dynamic Vehicle Force

Part of the Lecture Notes in Civil Engineering book series (LNCE, volume 253)EWSHM: European Workshop on Structural Health MonitoringThis study aims to investigate feasibility of a drive-by bridge inspection method using dynamic vehicle force. The dynamic vehicle force is identified using accelerations of a traveling vehicle. Dynamic vehicle forces when the vehicle travels on healthy and damage states of bridges are first identified. Differences of the identified dynamic vehicle forces from healthy and damage states of bridges are then considered as a damage sensitive feature for the drive-by bridge inspection. A least square minimization with Tikhonov regularization was utilized to estimate the dynamic vehicle force from acceleration data of the vehicle. A band pass filter is applied to the dynamic vehicle force before estimating the difference of the dynamic vehicle force. The range of the band pass filter was set around 1st natural frequency of the bridge. The feasibility of the proposed method was verified through simulation and a laboratory experiment. It was observed that the severer the bridge damage is, the larger the difference of dynamic vehicle force is, implying a possibility to detect bridge damages successfully by the proposed method

Morphological and molecular investigations of the holocephalan elephant fish nephron: the existence of a countercurrent-like configuration and two separate diluting segments in the distal tubule

In marine cartilaginous fish, reabsorption of filtered urea by the kidney is essential for retaining a large amount of urea in their body. However, the mechanism for urea reabsorption is poorly understood due to the complexity of the kidney. To address this problem, we focused on elephant fish (Callorhinchus milii) for which a genome database is available, and conducted molecular mapping of membrane transporters along the different segments of the nephron. Basically, the nephron architecture of elephant fish was similar to that described for elasmobranch nephrons, but some unique features were observed. The late distal tubule (LDT), which corresponded to the fourth loop of the nephron, ran straight near the renal corpuscle, while it was convoluted around the tip of the loop. The ascending and descending limbs of the straight portion were closely apposed to each other and were arranged in a countercurrent fashion. The convoluted portion of LDT was tightly packed and enveloped by the larger convolution of the second loop that originated from the same renal corpuscle. In situ hybridization analysis demonstrated that co-localization of Na(+),K(+),2Cl(-) cotransporter 2 and Na(+)/K(+)-ATPase α1 subunit was observed in the early distal tubule and the posterior part of LDT, indicating the existence of two separate diluting segments. The diluting segments most likely facilitate NaCl absorption and thereby water reabsorption to elevate urea concentration in the filtrate, and subsequently contribute to efficient urea reabsorption in the final segment of the nephron, the collecting tubule, where urea transporter-1 was intensely localized