Deterioration and Cavity of Surrounding Rocks at the Bottom of Tunnel Under the Combined Action of Heavy-Haul Load and Groundwater: An Experimental Study

In China, the first tunnel was built in accordance with the 30-ton heavy-haul railway standard. Based on the change in water and soil pressure obtained from long-term on-site monitoring, the cavity mechanism of the surrounding rock at the bottom of a heavy-haul railway tunnel under rich water conditions was explored in this study. The cavity characteristics and degradation depth of the three types of surrounding rock under different axial loads and hydrodynamic pressures were analyzed through laboratory tests. The structural defects at the bottom of the tunnel and local cracks in the surrounding rock were determined to provide a flow channel for groundwater. The dynamic load of heavy-haul trains causes groundwater to exert high hydrodynamic pressure on the fine cracks. The continuous erosion of the bottom surrounding rock leads to a gradual loss of surrounding rock particles, which would further exacerbate with time. The cohesive soil surrounding rock is noticeably affected by the combined action of heavy-haul load and groundwater in the three types of surrounding rock, and the surrounding rock cavity is characterized by overall hanging. In the simulation experiment, the particle loss of the surrounding rock reached 1,445 g, which is 24.2% higher than that of the pebble soil surrounding rock and 40.8% higher than that of sandy soil surrounding rock. The findings of this study could be helpful for developing methods for defect prediction and treatment of heavy-haul railway tunnels.

The Value of CT Radiomics Analysis of Cavity Characteristics In Differentiating Nontuberculous Mycobacteriumpulmonary Disease From Pulmonary Tuberculosis

Background: The CT features and clinical manifestations of the NTM pulmonary disease are similar to those of pulmonary tuberculosis (PTB), so it is very difficult to identify these two diseases simply via CT or clinical features.Methods: From February 2013 to March 2018, 73 patients of NTM pulmonary diseases and 69 patients of PTB with the cavity in Shandong Province Chest Hospital and Qilu Hospital of Shandong University were retrospctively analyzed. A double-blind assessment and manual delineation of 300 cavities as the region of interesting (ROI) from chest CT images were performed by 2 experienced radiologists. 80% of cavities were allocated to the training set and 20% to the validation set using a random number generated by a computer. 1409 radiomics features extracted from the Huiying Radcloud platform were used to analyze the two kinds of diseases' CT cavity characteristics. Feature selection was performed using analysis of variance (ANOVA) and least absolute shrinkage and selection operator (LASSO) methods, and six supervised learning classifiers (KNN, SVM, XGBoost，RF，LR , and DT models) were used to analyze the features, The Receiver Operating Characteristic (ROC), sensitivity and specificity were used to evaluate the model's performance.Results: 29 optimal features were selected by the variance threshold method, K best method, and Lasso algorithm.and the ROC curve values are obtained. In the training set, the AUC values of the six models were all greater than 0.97, 95% CI were 0.95-1.00, the sensitivity was greater than 0.92, and the specificity was greater than 0.92. In the validation set, the AUC values of the six models were all greater than 0.84, 95% CI were 0.76-1.00, the sensitivity was greater than 0.79, and the specificity was greater than 0.79.Conclusion: The radiomics features extracted from cavity on CT images can provide effective proof in distinguishing the NTM pulmonary disease from PTB, and the radiomics analysis shows a more accurate diagnosis than the radiologists .

Computational Study of Photonic Crystal Resonator for Biosensor Application

A two dimensional photonic crystal biosensor with high quality factor, transmission and sensitivity has been theoretically investigated using two dimensional finite difference time domain method (FDTD) and plane-wave expansion (PWE) approach. The studied biosensor consisted of two waveguide couplers and one microcavity formed by removing one air pore. Following analyte injection into the sensing holes and binding, the refractive index changes inducing a possible shift in the resonant wavelength. For the optimized structure, the biosensor quality factor is found to be over 49,767 and the obtained sensitivity is of order 15.2 nm/fg. Also, we investigated this structure in case of all air holes are applied as the functionalized holes with a sensitivity was found to be approximately equal to 292.46 nm∕RIU (refractive index units). According to the resonance cavity characteristics, the demultiplexing of different wavelengths can be achieved by regulating the radius of defects “r” inside the cavity. For this, A new design with 2D PCs for two-channel demultiplexer optofluidic biosensor has been proposed. The analysis shows that the response of each channel has a different resonant cavity wavelength and the filling of analyte in the selected holes cause resonant wavelength shifting, independently.

The Healthy Nasal Cavity—Characteristics of Morphology and Related Airflow Based on a Statistical Shape Model Viewed from a Surgeon's Perspective

Functional surgery on the nasal framework requires referential criteria to objectively assess nasal breathing for indication and follow-up. This motivated us to generate a mean geometry of the nasal cavity based on a statistical shape model. In this study, the authors could demonstrate that the introduced nasal cavity's mean geometry features characteristics of the inner shape and airflow, which are commonly observed in symptom-free subjects. Therefore, the mean geometry might serve as a reference-like model when one considers qualitative aspects. However, to facilitate quantitative considerations and statistical inference, further research is necessary. Additionally, the authors were able to obtain details about the importance of the isthmus nasi and the inferior turbinate for the intranasal airstream.