Related Experiment Video
Updated: Jan 25, 2026
10:52
Design, Instrumentation and Usage Protocols for Distributed In Situ Thermal Hot Spots Monitoring in Electric Coils using FBG Sensor Multiplexing
Published on: March 8, 2020
6.2K
Identification of Ground Intrusion inUnderground StructuresBased on Distributed Structural Vibration Detected by
Weibing Gan1, Sheng Li2, Zhengying Li3
1National Engineering Laboratory for Fiber Optic Sensing Technology, Wuhan University of Technology, Wuhan430070, Hubei, China. ganweibing@whut.edu.cn.
Sensors (Basel, Switzerland)
|May 12, 2019
Summary
Detecting illegal ground intrusions in subways is difficult. This study shows distributed fiber optic sensing can identify intrusion events, locate the area, and determine strength using vibration responses.
Area of Science:
- Geotechnical Engineering
- Structural Health Monitoring
- Fiber Optic Sensing
Background:
- Timely identification of illegal ground intrusions in underground systems like subways is crucial to prevent catastrophic tunnel collapse.
- Current methods may lack the precision and real-time capabilities needed for effective intrusion detection.
Purpose of the Study:
- To investigate the capability of distributed fiber optic sensing for detecting ground intrusions in subway tunnels.
- To assess the effectiveness of ultra-weak fiber Bragg grating (FBG) sensing in identifying intrusion characteristics.
Main Methods:
- Utilized an ultra-weak fiber Bragg grating (FBG) sensing fiber with five-meter spatial resolution in an actual subway tunnel.
- Simulated ground intrusion experiments using a hydraulic excavator with varying strengths and modes at five locations.
- Monitored distributed vibration responses from sensing fibers on the tunnel wall and track bed.
Main Results:
- Successfully detected the occurrence of simulated intrusion events.
- Accurately located the ground intrusion area.
- Distinguished between different intrusion strengths and perturbation modes based on vibration data.
Conclusions:
- Distributed fiber optic sensing, specifically FBG, is a viable method for real-time detection, localization, and characterization of ground intrusions in subway environments.
- The approach provides valuable data for preventing structural collapse due to unauthorized underground activities.
Related Concept Videos
03:21Weak Base Solutions
24.9K
Some compounds produce hydroxide ions when dissolved by chemically reacting with water molecules. In all cases, these compounds react only partially and so are classified as weak bases. These types of compounds are also abundant in nature and important commodities in various technologies. For example, global production of the weak base ammonia is typically well over 100 metric tons annually, being widely used as an agricultural fertilizer, a raw material for chemical synthesis of other...
24.9K
01:08Titration of a Weak Acid with a Weak Base
4.9K
Weak acids and bases do not undergo dissociation completely, and titrations between these two are rarely studied. When such studies are performed, say, for the titration of a weak acid with a weak base, the titration curve plots the change in pH as a function of the volume of base added. Take the titration of acetic acid with ammonia, for instance. During the titration, these two species form ammonium acetate and water, but the pH change is slow and gradual.
As a result, there is no simple...
As a result, there is no simple...
4.9K
03:55Titration Calculations: Weak Acid - Strong Base
49.1K
Calculating pH for Titration Solutions: Weak Acid/Strong Base
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as:
49.1K
02:22Structures of Solids
17.6K
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
17.6K
03:17Inheritance of Chromatin Structures
7.3K
Epigenetics is the study of inherited changes in a cell's phenotype without changing the DNA sequences. It provides a form of memory for the differential gene expression pattern to maintain cell lineage, position-effect variegation, dosage compensation, and maintenance of chromatin structures such as telomeres and centromeres. For example, the structure and location of the centromere on chromosomes are epigenetically inherited. Its functionality is not dictated or ensured by the underlying...
7.3K
02:34Structural Isomerism
21.5K
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
21.5K