Study on defects detection of a structure undergoing dynamic load

Damages detection method of a long span beam was studied. The beam was designed to subject vibration in order to simulate service station of a real structure. The distributed dynamic strain on the beam was studied. Firstly, in order to reduce the dynamic data discriminate time, a new BOTDA method using amplitude transfer of BFS was applied. At the level of spatial resolution of 10 cm and the sampling interval of 5 cm of the BOTDA system, a sampling frequency for dynamic strain of about 13 Hz was achieved. Secondly, a cracks detection system based on distributed dynamic strain was provided. Most of the time, a real structure is undergoing dynamic load, therefore crack detection system of analyzing distributed dynamic strain was concerned. The work is unlike former research that was based on the distributed static strain analysis. Thirdly, a free vibration experiment was performed on a beam of 15 meters long in order to verify the dynamic crack detection system. In order to local the crack easily, the data from BOTDA were processed. Fourier Transform Analysis was adopted to transfer the distributed dynamic strains from time domain into frequency domain. Test results indicated that the distributed frequency amplitude analysis method provided a practical means to recognize the simulated cracks on the beam undergoing dynamic displacement

Pedicled iliac crest bone flap transfer for the treatment of upper femoral shaft fracture nonunion: An anatomic study and clinical applications

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146632/1/micr30278.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146632/2/micr30278_am.pd

Analysis of high-position landslide characteristics based on multi-source remote sensing data：A case study of the Yanwo Village landslide in Rongshan Town, Lizhou District, Guangyuan City

On October 6, 2021, a high-position landslide disaster occurred in Yanwo Village，Rongshan Town, Lizhou District, Guangyuan City,Sichuan Province, around 13: 00. The landslide resulted in the destruction of 4 houses, 3 power lines, the burial of a 170-meter-long rural road, and the blockage of a 350-meter-long river channel. By utilizing a variety of remote sensing information sources, including multi-period satellite data before and after landslide, high-precision UAV aerial images, and airborne LiDAR data, the characteristics of high landslide and its sliding mode are studied by using a four-dimensional analysis approach combining three-dimensional space with time. Starting from the development background of high landslide, the deformation and failure characteristics and sliding mode of high landslide are summarized by analyzing the deformation characteristics before sliding and the dynamic procession of the high landslide. Based on the deduced landslide progression and the stability evaluation of the residual landslide at the rear, three sliding modes for future high-position landslide events are predicted and analyzed: Firstly, the back edge of landslide continues to be disjointed and move, causing a direct shear failure of the front part of the landslide by squeezing. Secondly, the trailing edge of the landslide continues to be disjointed and move, resulting in the sliding landslide occurs along the existing landslide channel. Thirdly, the initiation of the front part of the landslide trigger a tractional landslide in the middle and rear parts of the landslide. High-position landslides are common in the southwest mountainous areas, and during early geological hazard investigations, they should be effectively identified, and disaster prevention and mitigation measures should be strengthened

Polydatin Prevents Lipopolysaccharide (LPS)-Induced Parkinson's Disease via Regulation of the AKT/GSK3β-Nrf2/NF-κB Signaling Axis

Parkinson's disease (PD) is a common neurodegenerative disease characterized by selective loss of dopaminergic neurons in the substantia nigra (SN). Neuroinflammation induced by over-activation of microglia leads to the death of dopaminergic neurons in the pathogenesis of PD. Therefore, downregulation of microglial activation may aid in the treatment of PD. Polydatin (PLD) has been reported to pass through the blood-brain barrier and protect against motor degeneration in the SN. However, the molecular mechanisms underlying the effects of PLD in the treatment of PD remain unclear. The present study aimed to determine whether PLD protects against dopaminergic neurodegeneration by inhibiting the activation of microglia in a rat model of lipopolysaccharide (LPS)-induced PD. Our findings indicated that PLD treatment protected dopaminergic neurons and ameliorated motor dysfunction by inhibiting microglial activation and the release of pro-inflammatory mediators. Furthermore, PLD treatment significantly increased levels of p-AKT, p-GSK-3βSer9, and Nrf2, and suppressed the activation of NF-κB in the SN of rats with LPS-induced PD. To further explore the neuroprotective mechanism of PLD, we investigated the effect of PLD on activated microglial BV-2 cells. Our findings indicated that PLD inhibited the production of pro-inflammatory mediators and the activation of NF-κB pathways in LPS-induced BV-2 cells. Moreover, our results indicated that PLD enhanced levels of p-AKT, p-GSK-3βSer9, and Nrf2 in BV-2 cells. After BV-2 cells were pretreated with MK2206 (an inhibitor of AKT), NP-12 (an inhibitor of GSK-3β), or Brusatol (BT; an inhibitor of Nrf2), treatment with PLD suppressed the activation of NF-κB signaling pathways and the release of pro-inflammatory mediators in activated BV-2 cells via activation of the AKT/GSK3β-Nrf2 signaling axis. Taken together, our results are the first to demonstrate that PLD prevents dopaminergic neurodegeneration due to microglial activation via regulation of the AKT/GSK3β-Nrf2/NF-κB signaling axis

Investigations in Crack Detection and Monitoring Based on PPP-BOTDA Distributed Sensing Technology

Cracking is a common phenomenon in the structural members experiencing aging and deterioration problems. Structural health monitoring (SHM) based on crack detection and monitoring plays an important role in safety evaluation of the structures. Sensors developed from different technologies have been employed in crack detection and monitoring. Compared to point-style sensors, fiber optic distributed sensors have the advantage of performing ubiquitous sensing, which can locate the cracks directly. Brillouin scattering in optical fibers is sensitive to strain/temperature variations. One key factor affecting the performance of a Brillouin distributed sensing system is the spatial resolution (SR). Pre-pump-pulse Brillouin optical time domain analysis (PPP-BOTDA) is developed and capable of distributed strain/temperature sensing with centimeter-level SR. In this research, the capability of PPP-BOTDA in crack detection and monitoring is studied both theoretically and experimentally. Appearance of a crack in the structural member will create an extra strain distribution in the sensing fiber. The changes in Brillouin gain spectrum (BGS) induced by the extra strain are analyzed by numerical simulation and validated by the single-crack test. The changes in BGS are characterized by Brillouin frequency shift (BFS) and the difference in BGS width (BGSWD). Overall, results from the test match with calculation from numerical simulation. The crack is successfully detected as a peak from BFS and BGSWD. The widening of the crack can be monitored by the amplitude of the peak. Tests on structural members show that the SR employed will affect the performance of the sensing system when multi cracks appear. The capability of PPP-BOTDA system in differentiating neighboring cracks is studied through numerical simulation followed by experimental tests for a series of dual-crack cases considering different crack spacings. It is concluded that PPP-BOTDA can differentiate neighboring cracks when the SR employed is superior to the crack spacing. The conclusion from the dual-crack cases is validated by results from load tests of reinforced concrete (RC) beams. Based on the comprehensive research, better understanding of the results from the tests is achieved, and general guidance is provided for crack detection and monitoring with PPP-BOTDA distributed sensors

Experimental Study of Deep Submersible Structure Defect Monitoring Based on Flexible Interdigital Transducer Surface Acoustic Wave Technology

In view of the shortage of structural defect monitoring methods for deep submersibles, numerical simulation and experimental research on underwater SAW propagation based on interdigital transducers are carried out in this paper. PVDF interdigital transducer (PVDF-IDT) has shown considerable potential in the application of structural health monitoring because of its micro size, soft material characteristics, and the characteristics of long-term bonding on the surface of the tested structure. In order to realize the application of IDT on submersible or underwater structures, it is necessary to understand the influence of underwater environment on IDTs with different structures. The underwater attenuation of IDT with 2–5 mm wavelength and the underwater attenuation of Lamb (A0 mode) wave on a 4 mm thick titanium alloy plate is obtained through COMSOL software simulation. The experimental verification shows that the simulation results match with the actual situation, which proves that COMSOL software can accurately calculate the acoustic attenuation of surface waves at the solid–liquid interface. At the same time, the underwater attenuation of IDT with different structures is very different, providing important design parameters for the underwater interdigital transducer. In this paper, it is found that the Lamb wave has significant advantages over the Rayleigh wave in the health monitoring of underwater thin plate structures

CO₂ Injection Deformation Monitoring Based on UAV and InSAR Technology: A Case Study of Shizhuang Town, Shanxi Province, China

Carbon Capture, Utilization and Storage, also referred to as Carbon Capture, Utilization and Sequestration (CCUS), is one of the novel climate mitigation technologies by which CO2 emissions are captured from sources, such as fossil power generation and industrial processes, and further either reused or stored with more attention being paid on the utilization of captured CO2. In the whole CCUS process, the dominant migration pathway of CO2 after being injected underground becomes very important information to judge the possible storage status as well as one of the essential references for evaluating possible environmental affects. Interferometric Synthetic Aperture Radar (InSAR) technology, with its advantages of extensive coverage in surface deformation monitoring and all-weather traceability of the injection processes, has become one of the promising technologies frequently adopted in worldwide CCUS projects. In this study, taking the CCUS sequestration area in Shizhuang Town, Shanxi Province, China, as an example, unmanned aerial vehicle (UAV) photography measurement technology with a 3D surface model at a resolution of 5.3 cm was applied to extract the high-resolution digital elevation model (DEM) of the study site in coordination with InSAR technology to more clearly display the results of surface deformation monitoring of the CO2 injection area. A 2 km surface heaving dynamic processes before and after injection from June 2020 to July 2021 was obtained, and a CO2 migration pathway northeastward was observed, which was rather consistent with the monitoring results by logging and micro-seismic studies. Additionally, an integrated monitoring scheme, which will be the trend of monitoring in the future, is proposed in the discussion

Technical measures of deliverability enhancement for mature gas fields: A case study of Carboniferous reservoirs in Wubaiti gas field, eastern Sichuan Basin, SW China

Taking the carboniferous reservoir of Wubaiti gas field in eastern Sichuan Basin as an example, the technology strategies are proposed about the following major problems during the middle to late stage of gas field development: imbalance development, low permeability and low efficient reserves left with low producing degree, unreasonable proration caused by changes of gas well dynamic productivity, universal water production in gas wells, high reserve recovery and composite decline rate of reserve-rich region, and lack of new methods for reserves producing evaluation and remaining reserves distribution prediction. The development technical strategies for Wubaiti gas field are as follows: (1) stratigraphic subdivision and structural description in which fault and tectonic fluctuations are describe based on seismic interpretation data; (2) division and quantitative characterization of reservoir units in which the reservoir shape, scale, connectivity and gas-bearing range are evaluated according to dynamic and static data; (3) fluid distribution and dynamic response analysis in which gas-water distribution pattern is figured out by combining structure, reservoir and gas well production dynamic characteristics; (4) reserves producing degree evaluation and deliverability review in which reserves producing degree and remaining recoverable reserves scale are evaluated from the perspective of static geological reserves and dynamic reserves, to make clear the direction of the next step production and establish rational production system in the late stage; (5) static geological model establishment and dynamic correction in which gas reservoir pressure and remaining reserve distribution are predicted by using fine 3D geological modeling and numerical simulation; (6) remaining reserves prediction and classified evaluation based on the dynamic revision prediction model to guide the recovery of remaining reserves; and (7) gas production technology and equipment development, targeted gas recovery techniques are provided concerning the mature gas field. Key words: eastern Sichuan Basin, Wubaiti gas field, reservoir description, gas field development, remaining reserves, deliverability enhancement, technical strategie

Commensal Homeostasis of Gut Microbiota-Host for the Impact of Obesity

Gut microbiota and their metabolites have been linked to a series of chronic diseases such as obesity and other metabolic dysfunctions. Obesity is an increasingly serious international health issue that may lead to a risk of insulin resistance and other metabolic diseases. The relationship between gut microbiota and the host is both interdependent and relatively independent. In this review, the causality of gut microbiota and its role in the pathogenesis and intervention of obesity is comprehensively presented to include human genotype, enterotypes, interactions of gut microbiota with the host, microbial metabolites, and energy homeostasis all of which may be influenced by dietary nutrition. Diet can enhance, inhibit, or even change the composition and functions of the gut microbiota. The metabolites they produce depend upon the dietary substrates provided, some of which have indispensable functions for the host. Therefore, diet is a key factor that maintains or not a healthy commensal relationship. In addition, the specific genotype of the host may impact the phylogenetic compositions of gut microbiota through the production of host metabolites. The commensal homeostasis of gut microbiota is favored by a balance of microbial composition, metabolites, and energy. Ultimately the desired commensal relationship is one of mutual support. This article analyzes the clues that result in patterns of commensal homeostasis. A deeper understanding of these interactions is beneficial for developing effective prevention, diagnosis, and personalized therapeutic strategies to combat obesity and other metabolic diseases. The idea we discuss is meant to improve human health by shaping or modulating the beneficial gut microbiota

3D imaging characteristics of pore and fracture of tight sandstone in Baihetan reservoir area based on μCT technology

Microfocus X-ray CT scanning (μCT) is one of the most effective methods for visualization of pore-fracture structure in rock, and its effectiveness in 3d imaging of pore-fracture in tight sandstone should be further explored.Taking the tight sandstone at the dam site of Baihetan Hydropower Station as an example, the pore-fracture 3D imaging characteristics of samples with different scanning accuracy were explored by using ultra-high precision μCT technology and segmentation algorithm, and their influence on obtaining key structural information was analyzed by SEM test.The results show that the combined segmentation method of interactive threshold and Top-hat can extract the pore and fracture information of tight sandstone more accurately. The interactive threshold segmentation method is suitable for the extraction of large pore and fracture, and the Top-hat segmentation method is suitable for the extraction of small pore.Small pores and microcracks are very developed in tight sandstone structure, and there are many isolated pores. Compared with 1.5 μm scanning resolution, 0.62 μm scanning resolution presents a clearer pore network model, but due to the limited testing range at the nanoscale, the key structural information properties may be magnified.Critical microstructure information may be missed when the scanning resolution is greater than 2μm.Therefore, in the study of three-dimensional characteristics of pores and fractures in tight sandstone, high scanning accuracy should be selected and multi-region information acquisition should be carried out to effectively reveal the key microstructure features. This basic work provides a support for further effectively revealing the structural evolution information of tight rocks