Evolution of tunnels in alpha/beta-hydrolase fold proteins - what can we learn from studying epoxide hydrolases?

The evolutionary variability of a protein's residues is highly dependent on protein region and protein function. Solvent-exposed residues, excluding those at interaction interfaces, are more variable than buried residues. Active site residues are considered to be conserved as they ensure an enzyme's activity and selectivity. The abovementioned rules apply also to α/β-hydrolase fold proteins - an example of enzymes with buried active sites equipped with tunnels linking the reaction site with the exterior. We hypothesised two scenarios: (1) tunnels are lined by mostly variable residues, allowing adaptation to the evolutionary pressures of a changeable environment; or (2) tunnels are lined by mostly conserved amino acids, and are equipped with a number of specific variable residues that are able to respond to evolutionary pressure. We also wanted to check if evolutionary analysis can help distinguish functional and non-functional tunnels. Soluble epoxide hydrolases (sEHs) represent a good case study for the analysis of the evolution of tunnels in an α/β-hydrolase fold family due to their size and architecture. Here, we propose methods for the comparison of tunnels detected in both crystal structures and molecular dynamics simulations, as well as the assignment of tunnel functionality, and we identify critical steps for careful tunnel inspection. We also compare the entropy values of the tunnel-lining residues and system-specific compartments in seven selected sEHs from different clades. We present three different cases of entropy distribution among tunnel-lining residues. As a result, we propose a 'perforation' model for tunnel evolution via the merging of internal cavities or surface perforations. We also report an approach for the identification of highly variable tunnel-lining residues as potential targets to be used for the fine-tuning of selected enzymes.

3D Laser Triangulation and Deep Learning Approach to Tunnel Inspection

Regular inspection of tunnel surfaces is an important practice from both a safety and tunnel asset management perspective. However, inspection for cracking and spalling is still predominantly a manual task, which is time consuming, subjective, and exposes on-foot staff to risk. This presentation will explore the use of 3D laser scanning technology and artificial intelligence to automate the inspection process with a Canadian metro case study being presented.

Research on the Present Situation and Development Trend of Subway Tunnel Inspection Vehicle

For the operational subway tunnel, the manual inspection accounts for the majority in terms of detecting the diseases and damage of tunnel. The accuracy of manual inspection mainly depends on the professional level of the detection personnel, and the whole detection process always is inefficient, which cannot meet the needs of actual tunnels. To address this issue, the intelligent mobile tunnel detection vehicle emerges as the times require. By using advanced technologies such as laser scanning and high-speed camera array, the subway tunnel detection vehicle has achieved the advantages of simple operation, comprehensive function and automatic detection. However, the current subway tunnel detection vehicle mainly realizes the scanning detection of tunnel surface diseases, and the detection of tunnel structural diseases is less involved. Based on the track and tunnel detection requirements, this study analyzes the current situation and existing problems of subway tunnel detection comprehensively, puts forward the development direction of tunnel structure detection, and the application prospect of intelligent detection vehicle in subway tunnel is prospected.

Omnidirectional Robotic Platform for Surveillance of Particle Accelerator Environments with Limited Space Areas

Intelligent robotic systems are becoming essential for inspections and measurements in harsh environments. This article presents the design of an omnidirectional robotic platform for tunnel inspection with spatial limitations. This robot was born from the need to automate the surveillance process of the Super Proton Synchrotron (SPS) accelerator of the European Organization for Nuclear Research (CERN), where there is remaining radiation. The accelerator is located within a tunnel that is divided by small doors of 400 × 200 mm dimensions, through which the robot has to cross. The designed robot brings a robotic arm, and the needed devices to carry out the inspection. Thanks to this design, the robot application may vary by replacing certain devices and tools. In addition, this paper presents the kinematic and dynamic control models for the robotic platform.

Review of Post-Fire Inspection Procedures for Concrete Tunnels

It is well known that concrete structures can lose strength and long-term durability after a fire. The literature on the remaining capacity of tunnel structures after fire is quite scattered, however, and few published post-fire inspection guides exist. This paper reviews the available literature on the post-fire inspection and evaluation of concrete tunnels. The effects of fire on concrete and steel are discussed, including loss of strength, thermal spalling of concrete, and loss of strength in the bond between concrete and steel. In addition, studies on the residual strength of concrete members are presented. Available post-fire inspection strategies and methods are also discussed. Finally, the results of a survey of post-fire tunnel inspection practices at state Departments of Transportation and transit organizations across the United States are presented. Several models available in both structural building codes and experimental studies allow for the estimation of residual concrete compressive and steel tensile strength after heating and cooling from a given temperature. Furthermore, a variety of post-fire assessment methods are available, which include methods to assess the general post-fire condition of concrete tunnels, as well as methods to more directly assess the residual condition of concrete. Lastly, the review of literature and the survey of United States transit organizations revealed a lack of existing post-fire inspection procedures for concrete tunnels, and a need for further research on the subject.

Analysis on Treatment Effect of Mine Tunnel Construction Spring in Karst Area

The investigation of ultrashallow buried mining method in an interval revealed the existence of the karst fracture zone. The flow rate of 9 springs exposed in the initial excavation was relatively large, and the total water output per hour was nearly 300 m3. The filling materials in karst channels or fissures had the risk of bursting during excavation. Moreover, the ultrashallow buried tunnel undercrossed a special railway line, and the construction required higher surface deformation control. In view of the abovementioned risk problems, based on the grouting ideas of “assessment of influence,” “determination of surrounding rock,” “zone positioning,” and “dynamic grouting,” the grouting design scheme is dynamically optimized, and the grouting construction of surrounding water is cut off. Combined with the tunnel inspection, monitoring data, and numerical analysis, it is verified that the construction technology adopted in the project can ensure the stability of the project, which can provide a reference for similar projects.

A Train-Mounted GPR System for Operating Railway Tunnel Inspection

With the increasing number and aging of railway tunnels, regular inspection will be an important means to ensure the safety for operation railways. A train-mounted ground penetrating radar system with cores of air-coupled antennas and shared time-window model has been developed to allow for long-distance and fast inspection of tunnels. The system consists of 6 groups of air-coupled antennas with center frequency of 300 MHz. The distance between antenna and lining is 0.5–4.0 m, the scanning rate of the system is 976 scans/Sec and the detection depth of the GPR can reach to 2.5 m. Under the theoretical design, the maximum speed of train can reach 70.27 km/h with a scan interval of 0.02 m. The test results on Shenyang-Dandong railway passenger dedicated line show that the system can identify the thickness of lining, the void and the backfill state behind lining.